2012 · Q49
On walking 120 m towards a chimney in a horizontal line through its base the angle of elevation of tip of the chimney changes from 30 degrees to 45 degrees. The height of the chimney is:
Elementary MathematicsTrigonometry
- A120 m
- B60(sqrt(3)-1) m
- C60(sqrt(3)+1) m
- DNone of the above
Explanation
h/(h+120) = tan30 gives h = 120/(sqrt(3)-1) = 60(sqrt(3)+1) m.