### Home > CALC > Chapter 9 > Lesson 9.2.1 > Problem9-51

9-51.

Using summation notation, write a Riemann sum to represent the area under $f(x) = 2\operatorname{cos}^2 x − x$ from $- \frac { \pi } { 2 } \leq x \leq \frac { \pi } { 2 }$ using $6$ rectangles.

The length of the interval is $π$. Using $6$ rectangles, what is the width of each rectangle?