## anonymous 5 years ago Can someone tell me how can it be like this?please upload detailed answer http://imageshack.us/photo/my-images/843/dsc00441jz.jpg/

1. Owlfred

Hoot! You just asked your first question! Hang tight while I find people to answer it for you. You can thank people who give you good answers by clicking the 'Good Answer' button on the right!

2. watchmath

Recall that $$\cos(2x)=2\cos^2(x)-1$$ Plugin $$x=\theta/2$$ we have $$1+\cos(\theta)=2\cos^2(\theta/2)$$. When you take the square root of that you get $$\sqrt{2}\sqrt{\cos^2(\theta/2)}$$ and then this the two square roots become $$2$$ in the front of the integral.