While checking my works to my answers manual, I realized one of the steps I have a hard time understanding:

http://i36.tinypic.com/fclle8.jpghttp://i35.tinypic.com/2wnohhc.jpg

How did the integrals from pi/2 to 3pi/4 turn into 1 to rt2/2? I thought since u = sin x, doesn't x = pi/2 means that u = sin(3pi/4) = 1/rt2 instead of rt2/2?