Determine the trigonometric ratio to be used according to the information that is given.
45
Practice makes perfect
We are given the length of one of the legs and the hypotenuse of a right triangle, and want to find the measure of one of its acute angles ∠J.
Note that we are given the adjacent side of the unknown angle and the hypotenuse. Therefore, to find its measure, we will use the cosine ratio.
cos J = Adjacent/Hypotenuse ⇔ 17/24
The cosine of the angle is 1724. Now, to isolate m∠J, we will use the inverse function of cos.
cos J=17/24 ⇔ J=cos ^(- 1)17/24
Let's use a calculator to find the value of cos ^(- 1) 1724. First, we will set our calculator into degree mode. To do so, push MODE, select Degree instead of Radian in the third row, and push ENTER. Next, we push 2ND followed by COS, introduce the value 1724, and press ENTER.
