Determine the trigonometric ratio to use according to the given information and the unknown.
9.5
Practice makes perfect
We are given the length of hypotenuse and the measure of an acute angle of a right triangle. We want to find the length of one of the legs.
Note that the given side is the hypotenuse, and the side we want to find is adjacent to the given angle. Therefore, we will use the cosine ratio.
cos θ = Length of leg adjacent toθ/Length of hypotenuse
In our triangle, we have that θ =58^(∘) and the length of the hypotenuse is 18. We want to find the length of the leg adjacent to the angle.
