# Math Help - Integral question

1. ## Integral question

Use the Midpoint Rule with the given value of n to approximate the integral. Round the answer to four decimal places.
 π/2 2 cos5 x dx, n = 4 0

the midpoints I calculated to be Pi/16, 3pi/16, 5pi/16, and 7pi/16.

giving this: (pi/8) ((2 cos(pi/16))^5 + (2 cos^5(3 pi/16))^5 +(2 cos^5(5 pi/6))^5+(2 cos^5(7pi/16))^5

I calculated this to be 50.2345 , which according to the system is wrong. Where did I go wrong? Thanks for any help!

2. ## Re: Integral question

You made two mistakes I think.

To get the correct answer:

1) Set you calculator to radians.

2) Don't put the 2 in the bracket, in fact don't use the brackets there.

Try $\frac{\pi}{8}\left(2 \cos\left(\frac{\pi}{16}\right)^5+...$

Thanks!