Int[1/1+3cos^2(x)]dx integration

[rizardon]

Homework Statement

int[1/1+3cos^2(x)]dx

Homework Equations

The Attempt at a Solution

It shouldn't require any techniques of integration other than u-substitution. I tried letting u = sqrt(3)cos(x) and u = tan(x/2) but both didn't work so I think I need to multiply some expression by some term but I'm not quite sure what it is.

 

[Char. Limit]

You say that you tried u=tan(x/2), and it didn't work. But how much did you pursue this? Because the problem IS solvable using that substitution.