Two steel props cross at a single bolted joint on a building site, one prop running level and the other running diagonally. The angle between the level prop...
Question 1 Report
Two steel props cross at a single bolted joint on a building site, one prop running level and the other running diagonally. The angle between the level prop and the diagonal prop is \(115^{\circ}\), as shown.
Work out the size of angle \(x\). (2)
Answer Details
This question uses the vertically opposite angle rule where two straight props cross.
Angle \(x\) and the marked \(115^\circ\) angle are formed on opposite sides of the crossing point by the same two straight props, making them vertically opposite angles. [1 mark]
Vertically opposite angles are always equal, so \(x = 115^\circ\). [1 mark]
Vertically opposite angles arise whenever two straight lines cross: the two angle pairs facing each other across the intersection point are always equal, regardless of how steeply the lines cross.
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