### Home > CALC > Chapter 2 > Lesson 2.1.2 > Problem2-28

2-28.

Set up an equation using the Trapezoidal Rule that will approximate the area under $f(x) =\text{cos }x$ on $[ - \frac { \pi } { 2 } , \frac { \pi } { 2 } ]$ using six trapezoids with equal height. How could you use the fact that $\text{cos }x$ is an even function to save yourself some work?

Notice the symmetry about the $y$-axis. If we evaluate the trapezoidal sum on one side of the $y$-axis, can we determine the trapezoidal sum on the other side of the $y$-axis?