A 18 m long ladder (whose foot is on the ground) leans against a wall making…
2020
A 18 m long ladder (whose foot is on the ground) leans against a wall making an angle of 60° with the wall. What is the height (in m) of the point where the ladder touches the wall from the ground?
- A.
9√3
- B.
(9√3)/2
- C.
9√2
- D.
9
Show answer & explanation
Correct answer: D
Key idea: The ladder is the hypotenuse, and it makes a 60° angle with the vertical wall.
The required height is adjacent to the 60° angle at the wall.
Height = 18 cos 60° = 18 × 1/2 = 9 m.
Answer: Option 3, 9, is correct.