In △ △ XYZ, XY = 13cm, YZ = 9cm, XZ = 11cm and XYZ = θ θ . Find cosθ θ o

Question 1 Report

In $△$ XYZ, XY = 13cm, YZ = 9cm, XZ = 11cm and XYZ = $θ$ . Find cos $θ$ o

\frac{4}{39}

\frac{43}{39}

\frac{209}{3}

\frac{43}{78}

Answer Details

cos $θ$ = $\frac{13^{2} + 9^{2} - 11^{2}}{2 (13) (9)}$
= $\frac{169 + 81 - 21}{26 \times 9}$
cos $θ$ = $\frac{129}{26 \times 9}$
= $\frac{43}{78}$

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