Question

A wooden board is leaning against a wall. The base of the board is 6 feet from the base of the wall, and the base of the board forms a 55° angle with the ground.
What is the length of the wooden board?

Enter your answer, rounded to the nearest tenth, in the box.

Answer 1

The board is the hypotenuse of a right angle triangle. We know one side and one angle. The known side and angle are adjacent to each other so we can use the cos formula. The cos of an angle is the length of the adjacent side over the length of the hypotenuse.

CAH

Cos(55) = 6 / H
H = 6 / cos(55)
H = 10.46 or 10.5 inches (rounded)