Original problem:

Find the length of the curve. http://www.webassign.net/www29/symIm...851cf35972.gif

I have gotten this far:

but now I'm stuck because I don't perfectly recall the sin/cos/tan identities... I know that if I can get rid of the and I can change to , which I can get the square root of and solve for... but what identities do I need to use? Thanks for any help.