Answer:
≈ 20.8 ft
Step-by-step explanation:
A right triangle is formed between the wall, the ground and the ladder.
The ladder is the hypotenuse , the wall and ground are the legs.
let h be the height of the wall, then using Pythagoras' identity
h² + 33² = 39²
h² + 1089 = 1521 ( subtract 1089 from both sides )
h² = 432 ( take the square root of both sides )
h = ≈ 20.8 ft ( to the nearest tenth )