Answer:
The measure of angle R is
![22.62\°](https://img.qammunity.org/2020/formulas/mathematics/high-school/re75y1gng6kktnmxs25ghhkw6yfxbkf1os.png)
Explanation:
we know that
In the right triangle PQR
The cosine of angle R is equal to divide the adjacent side angle R by the hypotenuse
so
![cos(R)=(QR)/(PR)](https://img.qammunity.org/2020/formulas/mathematics/high-school/u162c5h16gbaxkeruk9d4gvee0ab1s5t92.png)
substitute the values
![cos(R)=(12)/(13)](https://img.qammunity.org/2020/formulas/mathematics/high-school/vtpus6k41ilks1yhxvrzflxbal2lxx12im.png)
![<R=arccos((12)/(13))=22.62\°](https://img.qammunity.org/2020/formulas/mathematics/high-school/v70zytin7789jur8qgurcxhel6935yh6ab.png)
see the attached figure to better understand the problem