You need to use the double angle formula:
hello , ive been stuck on this problem all night now. my heads starting to hurt lol. anyway im supposed to determine the area of the region by the graphs of the equations y=sin^2(pix) , y=0 , x=0 , x=1.
heres a link to what the equation looks like , just in case http://www.wolframalpha.com/input/?i=integrate+sin^2%28pi*x%29+dx+from+x%3D0+to+1
now, the answer i get is 3/4, which i think is wrong. i replaced sin^2(pix) with 1-cos^(pix).