Problem:
Use the Trapezoidal Rule to approximate the area bounded by the graph of

f(x) = cos3(x)

between x = 0 and x = 3 and the x-axis. Use N = 6 trapezoids.

Visualization:
Using Integral (from the University of Arizona):

1. After starting up the program, you are prompted "Would you like some instructions?" Use the arrow keys to move to either Yes or No and then press .
2. If you choose Yes then read the instructions and press when you are ready to proceed.
3. Use the arrow keys to highlight Create Integrals and press .
4. Use the arrow keys to highlight Create Integral and press .
5. At the prompt, Enter integrand:, type
(cos(x))^3 .
6. At the prompt, Lower x limit : -10, type .
7. At the prompt, Upper x limit : 10, type .
8. Use the arrow keys to move to Plot Integrand (Rectangle) and press .
9. At the prompt, Minimum y : -10, type .
10. At the prompt, Maximum y : 10, type .
11. You will now see the graph of the function.
12. Note that n=5. If you press uppercase then n is increased by 1 to 6.
13. Press for Trapezoid and you will get the following: