Trigonometric Functions on Right Triangles

8. Trigonometric Functions on Right Triangles / Trigonometric Functions on Right Triangles / Problem 3

Problem 3

Determine the exact value of the following expression without the help of the calculator.
cos 18° sin 72° + cos 72° sin 18°

-1

Determine the exact value of the following expression without the help of the calculator.cos 18° sin 72° + cos 72° sin 18°