2026 · Q44
At a point on level ground, the tangent of the angle of elevation of the top of a tower is found to be 5/6. On walking 70 m towards the tower, the tangent of the angle of elevation of the top of the tower is found to be 9/8. What is the height of the tower?
Elementary MathematicsTrigonometry
- A225 m
- B270 m
- C300 m
- D330 m
Explanation
Let the height be h and the original distance d: h/d=5/6 and h/(d−70)=9/8. From the first, d=6h/5; substituting gives 8h=9(6h/5−70), i.e. 630=14h/5, so h=225 m, option A.