JAMB UTME - Mathematics - 2017

Maelezo ya Majibu

Dividing polynomials is a process similar to dividing numbers. To divide 4x^3 - 3x + 1 by 2x - 1, we need to find a polynomial that when multiplied by 2x - 1 gives us 4x^3 - 3x + 1. The polynomial that fits the bill is 2x^2 + x - 1. This can be verified by multiplying 2x^2 + x - 1 by 2x - 1, which gives us 4x^3 - 3x + 1. Therefore, the answer is 2x^2 + x - 1.

Maelezo ya Majibu

The locus of a point that is equidistant from a line is a perpendicular bisector to the line. The perpendicular bisector of a line is a line that passes through the midpoint of the line and is perpendicular to it. In other words, the locus of a point that is equidistant from a line is a line that cuts the original line into two equal halves and is perpendicular to it.

Maelezo ya Majibu

Let's simplify each term first: - √27 can be simplified as √(3^3), which equals 3√3. - √12 can be simplified as √(2^2 × 3), which equals 2√3. - √75 can be simplified as √(3 × 5^2), which equals 5√3. Substituting these simplifications into the original expression, we get: 427(3√3) + 512(2√3) - 375(5√3) Simplifying the coefficients of √3, we get: 1281√3 + 1024√3 - 1875√3 Combining like terms, we get: 330√3 Therefore, the simplified expression is 330√3. Answer:  73" tabindex="0" class="mjx-chtml MathJax_CHTML" id="MathJax-Element-38-Frame">√3  divided by 3.

Maelezo ya Majibu

The operation * on the set R of real numbers is defined as x * y = 3x + 2y − 1. To find 3 * −1, we need to substitute x = 3 and y = −1 into the equation and simplify. So, we have: 3 * −1 = 3 * 3 + 2 * −1 − 1 = 9 + −2 − 1 = 6 So, the answer is 6.

Maelezo ya Majibu

The locus of a point P(x,y) such that PV = PW where V = (1,1) and W = (3,5). This means that the point P moves so that its distance from V and W are equidistance.
PV = PW
$\sqrt{(x-1{)}^2+(y-1{)}^2}=\sqrt{(x-3{)}^2+(y-5{)}^2}$.
Squaring both sides of the equation,
(x-1)2 + (y-1)2 = (x-3)2 + (y-5)2.
x2-2x+1+y2-2y+1 = x2-6x+9+y2-10y+25
Collecting like terms and solving, x + 2y = 8.

Maelezo ya Majibu

Let's denote the man's speed on his first trip as "s". On his first trip, he covered a distance of 50 miles, so his time would be: time = distance / speed = 50 / s On his later trip, he traveled 300 miles while going 3 times as fast, so his new speed would be: new speed = 3s His time for the later trip would then be: time = distance / speed = 300 / (3s) = 100 / s So the ratio of his new time to his old time would be: new time / old time = (100/s) / (50/s) = 100/50 = 2 Therefore, his new time compared to his old time is twice as much. In simpler terms, the man covered a longer distance on his second trip but also traveled faster. Even though he traveled faster on the second trip, the increased distance resulted in his new time being twice as much as his old time.

Maelezo ya Majibu

The gradient of a line is a measure of how steep the line is. It tells us the rate of change in the vertical direction for every unit change in the horizontal direction. To find the gradient of the line joining two points, we need to use the formula: Gradient = (Change in y-coordinate) / (Change in x-coordinate) = (y2 - y1) / (x2 - x1) Using this formula, the gradient of the line joining the points (3, 2) and (1, 4) is: Gradient = (4 - 2) / (1 - 3) = (2) / (-2) = -1 So, the gradient of the line joining the points (3, 2) and (1, 4) is -1.

Maelezo ya Majibu

Maelezo ya Majibu

To evaluate the given expression step-by-step, let's break it down:

$1-(\frac{1}{5}\times \frac{2}{3})+{\left(\frac{5+\frac{2}{3}}{4}\right)}^{3}1\; -\; \backslash left(\; \backslash frac\{1\}\{5\}\; \backslash times\; \backslash frac\{2\}\{3\}\; \backslash right)\; +\; \backslash left(\; \backslash frac\{5\; +\; \backslash frac\{2\}\{3\}\}\{4\}\; \backslash right)^3$

Step 1: Evaluate $\frac{1}{5}\times \frac{2}{3}\backslash frac\{1\}\{5\}\; \backslash times\; \backslash frac\{2\}\{3\}$

$\frac{1}{5}\times \frac{2}{3}=\frac{1\times 2}{5\times 3}=\frac{2}{15}\backslash frac\{1\}\{5\}\; \backslash times\; \backslash frac\{2\}\{3\}\; =\; \backslash frac\{1\; \backslash times\; 2\}\{5\; \backslash times\; 3\}\; =\; \backslash frac\{2\}\{15\}$

51​×32​=5×31×2​=152​

Step 2: Subtract $\frac{\mathrm{<span\; style="font-family:\; Ubuntu;\; font-size:\; 16px;">2</span>}}{\mathrm{<span\; style="font-family:\; Ubuntu;\; font-size:\; 16px;">15</span>}}$\frac{2}{15} from 1

$1-\frac{2}{15}=\frac{15}{15}-\frac{2}{15}=\frac{13}{15}1\; -\; \backslash frac\{2\}\{15\}\; =\; \backslash frac\{15\}\{15\}\; -\; \backslash frac\{2\}\{15\}\; =\; \backslash frac\{13\}\{15\}$

Step 3: Simplify

$\frac{5+\frac{2}{3}}{4}\backslash frac\{5\; +\; \backslash frac\{2\}\{3\}\}\{4\}$

First, convert $55$ to a fraction with a denominator of 3:

$5=\frac{15}{3}5\; =\; \backslash frac\{15\}\{3\}$

So,

$5+\frac{2}{3}=\frac{15}{3}+\frac{2}{3}=\frac{17}{3}5\; +\; \backslash frac\{2\}\{3\}\; =\; \backslash frac\{15\}\{3\}\; +\; \backslash frac\{2\}\{3\}\; =\; \backslash frac\{17\}\{3\}$

Then divide by 4:

$\frac{17}{3}÷4=\frac{17}{3}\times \frac{1}{4}=\frac{17}{12}\backslash frac\{17\}\{3\}\; \backslash div\; 4\; =\; \backslash frac\{17\}\{3\}\; \backslash times\; \backslash frac\{1\}\{4\}\; =\; \backslash frac\{17\}\{12\}$

Step 4: Cube $\frac{\mathrm{<span\; style="font-size:\; 16px;">17</span>}}{\mathrm{<span\; style="font-size:\; 16px;">12</span>}}$\frac{17}{12}

${\left(\frac{17}{12}\right)}^3=\frac{17^3}{12^3}=\frac{4913}{1728}\backslash left(\; \backslash frac\{17\}\{12\}\; \backslash right)^3\; =\; \backslash frac\{17^3\}\{12^3\}\; =\; \backslash frac\{4913\}\{1728\}$

Step 5: Combine the results

$\frac{13}{15}+\frac{4913}{1728}\backslash frac\{13\}\{15\}\; +\; \backslash frac\{4913\}\{1728\}$

To combine these fractions, find a common denominator. The least common multiple of 15 and 1728 is 1728 (since 15 is a factor of 1728):

Convert $\frac{13}{15}\backslash frac\{13\}\{15\}$ to a fraction with a denominator of 1728:

$\frac{13}{15}=\frac{13\times 115.2}{15\times 115.2}=\frac{1497.6}{1728}\backslash frac\{13\}\{15\}\; =\; \backslash frac\{13\; \backslash times\; 115.2\}\{15\; \backslash times\; 115.2\}\; =\; \backslash frac\{1497.6\}\{1728\}$

Now add the fractions:

$\frac{1497.6}{1728}+\frac{4913}{1728}=\frac{1497.6+4913}{1728}=\frac{6410.6}{1728}\backslash frac\{1497.6\}\{1728\}\; +\; \backslash frac\{4913\}\{1728\}\; =\; \backslash frac\{1497.6\; +\; 4913\}\{1728\}\; =\; \backslash frac\{6410.6\}\{1728\}$

Simplifying the fraction is a bit complex and since none of the provided options directly match our detailed calculation, it looks like we might need to revisit some steps or compare our answer directly to the provided options to see if any approximation matches closely.

Given the complexity, let's directly compare the options:

Considering the given options, the closest approximate value

we calculated is around $\frac{6410.6}{1728}\backslash frac\{6410.6\}\{1728\}$ which seems close to $3.73.7$.

Hence, the closest match would be: 

$\boxed{{\displaystyle 3\frac{2}{3}}}\backslash boxed\{3\; \backslash frac\{2\}\{3\}\}$

Maelezo ya Majibu

The value of p can be found by solving for p when the two equations intersect at x=2. To do this, we first need to find the y-values for both equations when x=2. When x=2, the first equation becomes: y = p * 2^2 + q = 4p + q And the second equation becomes: y = 2 * 2^2 - 1 = 7 Now we have two equations with two unknowns (p and q) and we can use substitution to solve for p. We substitute the value of y from the second equation into the first equation: 4p + q = 7 And then we can isolate p by subtracting q from both sides: 4p = 7 - q And finally, dividing both sides by 4: p = (7 - q) / 4 So the answer is: p = (7 - q) / 4.

Maelezo ya Majibu

The sum of the range of a set of numbers is simply the difference between the largest and smallest number in the set. To find the mode, we need to look for the number that appears most frequently in the set. In this set of numbers, the smallest number is 4 and the largest number is 10, so the range would be 10 - 4 = 6. The mode of this set is the number 10, since it appears the most times (7 times). So, the sum of the range and the mode of the set is 6 + 10 = 16.

Maelezo ya Majibu

$\frac{2\sqrt{3}-\sqrt{2}}{\sqrt{3}+2\sqrt{2}}$= m + n√6
$\frac{2\sqrt{3}-\sqrt{2}}{\sqrt{3}+2\sqrt{2}}$ x $\frac{\sqrt{3}-2\sqrt{2}}{\sqrt{3}-\sqrt{2}}$

$\frac{2\sqrt{3}(\sqrt{3}-2\sqrt{2})-\sqrt{2}(\sqrt{3}-2\sqrt{2})}{\sqrt{3}(\sqrt{3}-2\sqrt{2})+2\sqrt{2}(\sqrt{3}-2\sqrt{2})}$
$\frac{2\times 3-4\sqrt{6}-6+2\times 2}{3-2\sqrt{6}+2\sqrt{6}-4\times 2}$
= $\frac{6-4\sqrt{6}-\sqrt{6}+4}{3-8}$
= $\frac{0-4\sqrt{6}-6}{5}$
= $\frac{10-5\sqrt{6}}{5}$
= − 2 + √6
∴ m + n$\sqrt{6}$ = − 2 + √6
m = − 2, n = 1

Maelezo ya Majibu

The expression 0.00000231 divided by 0.007 can be evaluated by dividing the numerator and denominator. The answer is a decimal, which can be written in scientific notation, also known as standard form, for easier reading. Scientific notation is a way of writing very small or very large numbers by multiplying a number between 1 and 10 by 10 raised to a power. In scientific notation, the answer to 0.00000231 divided by 0.007 is 3.3 x 10^4.

Maelezo ya Majibu

Total cost = N(250,000 + 70,000) = ₦320,000
Selling price = ₦400,000 (given)
Gain = SP - CP = N(400,000 - 320,000) = ₦80,000
Gain % = gain/CP x 100 = (80,000/320,000) x 100
Gain % = 25%

Maelezo ya Majibu

When two quantities, such as x and y, are inversely proportional, it means that as one quantity increases, the other quantity decreases at a consistent rate. In mathematical terms, we can write the inverse proportionality as: y = k/x where k is a constant of variation that relates the two quantities. To find the constant of variation, we can use the given information that "y and 6 when x = 7". Substituting these values into the equation, we get: 6 = k/7 Multiplying both sides by 7, we obtain: k = 42 Therefore, the constant of variation is 42, and the answer is.

Maelezo ya Majibu

Maelezo ya Majibu

To solve this problem, we substitute x = 2 into the given expression: x + x(x*x) = 2 + 2(2*2) = 2 + 2(4) = 2 + 8 = 10. Therefore, the value of x + x(x*x) when x = 2 is 10. Here's a step-by-step breakdown of how we got this answer: 1. We start by substituting the value of x into the expression, which gives us: x + x(x*x) = 2 + 2(2*2) 2. We simplify the expression inside the parentheses first, which gives us: x + x(4) 3. Then we multiply x by 4, which gives us: x + 4x 4. We combine the two terms to get: 5x 5. Finally, we substitute x = 2 into this expression, which gives us: 5(2) = 10 Therefore, the value of x + x(x*x) when x = 2 is 10.

Maelezo ya Majibu

The range is the difference between the highest and lowest values in a set. To find the range of the given set of numbers, we need to first find the highest and lowest values. The lowest value in the set is 4, while the highest value is 10. Therefore, the range is 10 - 4 = 6. The mode is the value that appears most frequently in a set. To find the mode of the given set of numbers, we need to count how many times each value appears and find the value that appears most frequently. The value 10 appears 5 times in the set, which is more than any other value. Therefore, the mode of the set is 10. To find the sum of the range and the mode, we simply add the two values together. In this case, the range is 6 and the mode is 10, so the sum is 6 + 10 = 16. Therefore, the correct answer is: 16.

Maelezo ya Majibu

The integral of x^2 + 3x - 5 with respect to x is: ∫(x^2 + 3x - 5) dx To solve this, we can use the power rule of integration, which states that the integral of x^n with respect to x is (x^(n+1))/(n+1) + C, where C is the constant of integration. Using this rule, we can integrate each term of the polynomial separately: ∫(x^2 + 3x - 5) dx = ∫x^2 dx + ∫3x dx - ∫5 dx = (x^3/3) + (3x^2/2) - (5x) + C Therefore, the antiderivative or indefinite integral of x^2 + 3x - 5 with respect to x is: (x^3/3) + (3x^2/2) - (5x) + C, where C is the constant of integration.

Maelezo ya Majibu

To find the product of (2x^2 - x + 1) and (3 - 2x), we need to multiply every term in the first expression with every term in the second expression, and then simplify the result. We can use the distributive property of multiplication to do this. First, we multiply 2x^2 by 3 and by -2x: 2x^2 * 3 = 6x^2 2x^2 * -2x = -4x^3 Then, we multiply -x by 3 and by -2x: -x * 3 = -3x -x * -2x = 2x^2 Finally, we multiply 1 by 3 and by -2x: 1 * 3 = 3 1 * -2x = -2x Now we can add up all these products: 6x^2 - 4x^3 - 3x + 2x^2 + 3 - 2x Simplifying this expression, we get: -4x^3 + 8x^2 - 5x + 3 Therefore, the answer is option B: -4x^3 + 8x^2 - 5x + 3.

Maelezo ya Majibu

Maelezo ya Majibu

M = $\frac{\sqrt{SL}}{T}$,
make T subject of formula square both sides
M2 = $\frac{N^{2}SL}{T}$
TM2 = N2SL
T = $\frac{N^{2}SL}{M^2}$

Maelezo ya Majibu

2x + x = 180°, => 3x = 180°, and thus x = 60°
Each exterior angle = 60° but size of ext. angle = 360°/n
Therefore 60° = 360°/n
n = 360°/60° = 6 sides

Maelezo ya Majibu

Percentage error is a measure of how accurately a measurement represents the true value of a quantity. It is calculated as the difference between the measured value and the true value, divided by the true value, and multiplied by 100 to get a percentage. In this case, the true value of the rod's length is 10 cm and the measured value is 10.5 cm. To calculate the percentage error, we use the formula: Percentage error = (|measured value - true value| / true value) * 100 = (|10.5 - 10| / 10) * 100 = (0.5 / 10) * 100 = 5% Therefore, the percentage error is 5%.

Maelezo ya Majibu

Total angle at a point = 3600
∴ To get the angle occupied by fertilizer we have,
40 + 50 + 80 + 70 + 30 + fertilizer(x) = 360
270 + x = 360
x = 360 - 270
x = 90
Total amount allocated to the farm
= ₦ 80,000
∴Amount allocated to the fertilizer
= $\frac{\text{fertilizer (angle) × Total amount}}{\text{total angle}}$
= $\frac{90}{360}$ × 80,000
= ₦20,000

Maelezo ya Majibu

To find the size of angle x, we can start by using the fact that the sum of the opposite angles in an inscribed quadrilateral is 180 degrees. In this case, angle RST is opposite to angle O, and angle OST is opposite to angle x. We are given that angle RST is 60 degrees, so we can use this to find angle O: angle RST + angle RTO + angle STO + angle OST = 360 degrees 60 + angle RTO + angle STO + angle OST = 360 angle RTO + angle STO + angle OST = 300 Since angle RTO and angle STO are both equal to angle O (because they are both subtended by the same arc), we can write: 3 x angle O = 300 angle O = 100 degrees Now that we know angle O, we can find angle x: angle OST = 180 - angle RST - angle O angle OST = 180 - 60 - 100 angle OST = 20 degrees Therefore, the size of angle x is 20 degrees, which corresponds to option D.

Maelezo ya Majibu

3${}^{n+1}$ × 27$\frac{n+1}{{81}^n}$
= 3${}^{n+1}$ × 3 $\frac{3^{(n+1)}}{3^{4n}}$
= 3${}^{n+1+3n+3-4n}$
= 3${}^{4n-4n-1+3}$
= 32
= 9

Maelezo ya Majibu

The range of a set of numbers is the difference between the largest and smallest values in the set. To find the range of the given set of numbers 0.4, -0.4, 0.3, 0.47, -0.53, 0.2, and -0.2, we need to find the largest and smallest values in the set. The largest value in the set is 0.47, and the smallest value in the set is -0.53. Therefore, the range of the set is: Range = largest value - smallest value = 0.47 - (-0.53) = 1.0 So the correct answer is: 1.0

Maelezo ya Majibu

We can use the formula for the volume of a cylinder to solve this problem. The formula is: Volume = πr^2h where π is the value of pi, r is the radius of the base, h is the height (or depth) of the cylinder. We are given that the diameter of the base of the cylinder is 14 m, which means the radius is 7 m (since radius is half the diameter). We are also given that the volume of the cylinder is 3080 m^3. Substituting these values into the formula, we get: 3080 = (22/7) * 7^2 * h Simplifying this expression, we get: 3080 = 22 * 7 * h 3080 = 154h h = 3080/154 h = 20 Therefore, the depth of the cylinder is 20 m, which means the answer is option C: 20 m.

Maelezo ya Majibu

To simplify the expression (643a3)−1, we can first simplify the term under the cube root sign. The cube root of 64a^3 is equal to the cube root of 64 multiplied by the cube root of a^3. The cube root of 64 is 4 because 4 x 4 x 4 = 64, and the cube root of a^3 is a multiplied by the cube root of a. Therefore, the term simplifies to 4a(cuberoot(a)). So, now we have (3√(4a(cuberoot(a))))^-1. To simplify this further, we can use the rule that (a/b)^-1 = b/a. Applying this rule to the expression, we get: 1 / (3√(4a(cuberoot(a)))) = (3√(4a(cuberoot(a))))^(-1) = 1 / (4a(cuberoot(a))) Therefore, the simplified expression is 1 / (4a(cuberoot(a))) or equivalently (1/4)(cuberoot(a^-2)). So the correct answer is 1/4cuberoot(a^-2), which can also be written as 14a.

Maelezo ya Majibu

?

$1?(\frac{1}{5}\times \frac{2}{3})+(5+\frac{2}{3})1\; -\; \backslash left(\; \backslash frac\{1\}\{5\}\; \backslash times\; \backslash frac\{2\}\{3\}\; \backslash right)\; +\; \backslash left(\; 5\; +\; \backslash frac\{2\}\{3\}\; \backslash right)$

Step 1: Evaluate $\frac{1}{5}\times \frac{2}{3}\backslash frac\{1\}\{5\}\; \backslash times\; \backslash frac\{2\}\{3\}$

$\frac{1}{5}\times \frac{2}{3}=\frac{1\times 2}{5\times 3}=\frac{2}{15}\backslash frac\{1\}\{5\}\; \backslash times\; \backslash frac\{2\}\{3\}\; =\; \backslash frac\{1\; \backslash times\; 2\}\{5\; \backslash times\; 3\}\; =\; \backslash frac\{2\}\{15\}$

51?×32?=5×31×2?=152?

Step 2: Subtract $\frac{2}{15}\backslash frac\{2\}\{15\}$ from 1

$1?\frac{2}{15}=\frac{15}{15}?\frac{2}{15}=\frac{13}{15}1\; -\; \backslash frac\{2\}\{15\}\; =\; \backslash frac\{15\}\{15\}\; -\; \backslash frac\{2\}\{15\}\; =\; \backslash frac\{13\}\{15\}$

1?152?=1515??152?=1513?

Step 3: Simplify $5+\frac{2}{3}5\; +\; \backslash frac\{2\}\{3\}$

First, convert $55$ to a fraction with a denominator of 3:

$5=\frac{15}{3}5\; =\; \backslash frac\{15\}\{3\}$

So,

$5+\frac{2}{3}=\frac{15}{3}+\frac{2}{3}=\frac{17}{3}5\; +\; \backslash frac\{2\}\{3\}\; =\; \backslash frac\{15\}\{3\}\; +\; \backslash frac\{2\}\{3\}\; =\; \backslash frac\{17\}\{3\}$

Step 4: Combine the results

$\frac{13}{15}+\frac{17}{3}\backslash frac\{13\}\{15\}\; +\; \backslash frac\{17\}\{3\}$

To combine these fractions, find a common denominator. The least common multiple of 15 and 3 is 15:

Convert $\frac{17}{3}\backslash frac\{17\}\{3\}$ to a fraction with a denominator of 15:

$\frac{17}{3}=\frac{17\times 5}{3\times 5}=\frac{85}{15}\backslash frac\{17\}\{3\}\; =\; \backslash frac\{17\; \backslash times\; 5\}\{3\; \backslash times\; 5\}\; =\; \backslash frac\{85\}\{15\}$

Now add the fractions:

$\frac{13}{15}+\frac{85}{15}=\frac{13+85}{15}=\frac{98}{15}\backslash frac\{13\}\{15\}\; +\; \backslash frac\{85\}\{15\}\; =\; \backslash frac\{13\; +\; 85\}\{15\}\; =\; \backslash frac\{98\}\{15\}$

Simplify the fraction if possible:

$\frac{98}{15}=6\frac{8}{15}\backslash frac\{98\}\{15\}\; =\; 6\; \backslash frac\{8\}\{15\}$

Thus, the evaluated expression is:

$\boxed{{\displaystyle 6\frac{8}{15}}}\backslash boxed\{6\; \backslash frac\{8\}\{15\}\}$

Maelezo ya Majibu

Principal, P = Amount, A - Interest, I.
A = P + I
I = (P.T.R)/100 = (P x 5 x 2)/100 = 10P/100 = P/10
But A = P + I,
=> 5500 = P + (P/10)
=> 55000 = 10P + P
=> 55000 = 11P
Thus P = 55000/11 = ₦5,000

Maelezo ya Majibu

MN || PQ || RS
MN = PQ = RS (parallel lines)
Label the angle in the lines
a = i (corresponding angles are equal)
b = x (corresponding angles are equal)
If |MN| = |RS|
If a = i
and a = 63 = i
a + b = 180 (Adjacent interior angles are supplementary i.e add to 180)
∴ i + x = 180
63 + x = 180
x = 180 - 63
x = 1170

Maelezo ya Majibu

Sum of angle at a point = 360o
2x + 3x + 4x = 360
9x = 360
x = $\frac{360}{9}$
x = 40o

Maelezo ya Majibu

Sum to infinity
? = arn ? 1
= $\frac{a}{1}$ ? r
a = $\frac{1}{4}$
r = $\frac{1}{8}$ ÷ $\frac{1}{4}$
r = $\frac{1}{s}$ × $\frac{4}{1}$
= $\frac{1}{2}$
S = $\frac{1÷4}{1}$ ? $\frac{1}{2}$
= $\frac{1}{4}$ ÷ $\frac{1}{2}$
= $\frac{1}{4}$ × $\frac{2}{1}$
= $\frac{1}{2}$

Maelezo ya Majibu

m * n = $\frac{m}{n}$ - $\frac{m}{n}$
m = − 3
n = 4
∴ − 3 × 4 = $\frac{-3}{4}$ - $\frac{-4}{-3}$
= $\frac{3(-3)-(-4\times 4)}{12}$
= $\frac{-9+16}{12}$
= $\frac{7}{12}$

Maelezo ya Majibu

Maelezo ya Majibu

MACICITA is an eight letter word = 8!
Since we have repeating letters, we have to divide to remove duplicates accordingly. There are 2A, 2C, 2I
∴ $\frac{8!}{2!2!2!}$

Maelezo ya Majibu

Maelezo ya Majibu

From the diagram

sin 70o = $\frac{x}{10}$

x = 10sin 70o

= 9.3969

Hence, length of chord MN = 2x

= 2 x 9.3969

= 18.7938

= 19cm (nearest cm)