Can Weierstrass Substitution Solve This Definite Integral?

[zhiyuanhou]

Hi everyone, when I was dealing with a physics problem, I find a definite integral and I cannot solve it.
$\int_{0}^{2\pi}$$\frac{1}{(a+cosx)^{2}}$dx
a is constant.
Thank you!

 

[micromass]

Perhaps try Weierstrass substitution. http://en.wikipedia.org/wiki/Weierstrass_substitution

 

[zhiyuanhou]

ha ha! Weierstrass substitution is well! Thank you!