The diagram shows a vertical wind turbine with blades 30m long. The blades are stationary with the point A being the maximum distance possible from the horizontal ground. The point B is such that the angle of elevation of A from B is 34° and the angle of elevation of the centre of the blades, C, from B is 25°. Calculate the distance AB. [Figure 9.1]

1. (a)The diagram shows a vertical wind turbine with blades 30m long. The blades are stationary with the point A being the maximum distance possible from the horizontal ground. The point B is such that the angle of elevation of A from B is 34° and the angle of elevation of the centre of the blades, C, from B is 25°. Calculate the distance AB. [Figure 9.1][3]
2. (b)A different wind turbine, shown in the diagram on the next page, has the centre of its blades, F, 75 m from the base of the turbine, D. Point E is on sloping ground, 180m from F and 130m from D. Calculate the angle of depression of E from F. [Figure 9.2][4]
3. (c)(i)P is the point on a blade which is furthest from the centre of the blades. Each blade is 30m long. Calculate the distance travelled by P as the blade completes one revolution.[1]
4. (c)(ii)The blade completes 15 revolutions per minute. Calculate the speed of P, giving your answer in kilometres per hour.[2]
5. (c)(iii)A point Q lies on the straight line between P and the centre of the blades. Q travels 90m as the blade completes one revolution. Calculate PQ.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.