Note that we are given the adjacent side to the unknown angle and the hypotenuse. Therefore, to find the measure of the angle we will use the cosine ratio.
cos x = Length of leg adjacent tox/Length of hypotenuse
In our triangle, we have that the length of the adjacent leg to x and hypotenuse are 31 and 64.
The cosine of the angle is 3164. Now, to isolate x we will use the inverse function of cos.
cos x=31/64 ⇔ x=cos ^(- 1)31/64
Let's use a calculator to find the value of cos ^(- 1) 3164. 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 3164, and press ENTER.
