Originally Posted by Cepheid
Since I feel lazy try this.
Go to wolfram alpha.com
Type in integrate (function here) into the box. It will compute the answer. Hit show steps.
Second one is by subsitution of u=cosx
Or realizing the what the derivative of cos^3(x) is, messing around with the constants and applying the fundamental theorem of calculus.
ah thx, that site helped alot