Question

Write each ratio using the given figure. If necessary, find the missing side.Cos R = __________

Answer 1

9/41

EXPLANATION :

Using Pythagorean Theorem to find the other side of the triangle :

`\begin{gathered} PR^2=QP^2+QR^2 \\ 41^2=40^2+QR^2 \\ 1681=1600+QR^2 \\ QR^2=81 \\ QR=√(81) \\ QR=9 \end{gathered}`

Recall that cos angle is adjacent over hypotenuse

The adjacent side to angle R is QR and the hypotenuse is RP

That will be :

`\cos R=(QR)/(RP)=(9)/(41)`