### Home > A2C > Chapter 14 > Lesson 14.9.2.1 > Problem 9-70

9-70.

Let .

Find the exact value of the average rate of change of

fromto . Write the expression for the average rate of change of

fromto . Use the fact that

to show that the expression in part (b) can be written as . Substitute values for the trigonometric expressions and simplify.