A and B are two points on the same side of a ground, 50 metres apart. The angles of elevation of these points to the top of a tree are 60° and 30°, respectively. What is 40% of te height of te tree(in m)?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 10
Let the height of the tree be H and the distance between the foot of the tree to the point A be x
Now,
H/x = tan 60 = (3)½
⇒ H/x = (3)½x
Again,
H/(x + 50) = tan 30
⇒ H/(x + 50) = 1/(3)½
H = (x + 50)/(3)½
Now,
(3)½ = (x + 50)/(3)½
⇒ 3x = x + 50
⇒ 2x = 50
⇒ x = 25
Now,
H/25 = (3)½
⇒ H = 25(3)½
Now,
40% of the height of the tree = 25(3)½ × 40% = 10(3)½