Question 1106079
.
Read the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/Trigonometry-basics/Evaluating-trigonometric-expressions.lesson>Evaluating trigonometric expressions</A>, Problem 1

in this site.


It is your sample: very similar problem was solved there.


After reading, solve your problem in the same way.