Going back over textbook problems and having a bit of trouble with this one.

If v=ai+bj, show that a/((a^2+b^2)^1/2)=Cos theta & b/((a^2+b^2)^1/2)=Sin theta, where theta is the direction of v.

Sorry if the question is not written the best. Newbie to the site. Thanks for your help in advance.