Feel free to call me a tard but I'm stumped on this definite

http://mathworld.wolfram.com/Double-AngleFormulas.html

Okay, step one is to take the constant out
so move the 64pi/25 out of the integral
64pi/25(integ)cos^2(x)dx

Step two: Use the double angle formula to get
cos^2(x)=(1+cos2x)/2
then take that constant out.
Now you have
32pi/25(integ)1+cos2xdx

Step 3 integrate and plug in definite values
(sum of the integrals is integrals of the sum)

(32pi/25)(x+1/2sin(2x)) + C
plug in the bounds^^

>>8714848
How can cos^2 be written, master?1

>>8714861
Cos^2(x) = (1 + Cos(2x) / 2

Check your trig identities, particularly your double angle formulas.

>>8714871
Oops, my mistake

= (1 + Cos(2x)) / 2
missed a parenthesis

A good resource that will show you ALL of the steps for integration would be this site:
http://www.integral-calculator.com/
or
https://www.symbolab.com/solver/definite-integral-calculator

These sites show you all of the steps for free (unlike wolfram)

>>8714790
Double angle formula is easiest.

If you can't remember that, just do integration by parts twice until you get the same integral, then do some algebra.