How to evaluate $\int \frac {dx}{\cos x+C}$? I want to evaluate  -

$$\int \frac {dx}{\cos x+C}$$

Where $C$ is an arbitrary constant.I tried substitution and parts but could not do it.
Note that for $C=1$ one can simply do this by using compound angle formulas.But what about other values of $C $?
Thanks for any help!!

Hint:
Make the substitution $ \theta = \frac{x}{2}$.
\begin{align}
\frac{1}{C + \cos 2 \theta} &= \frac{1}{C -1 + 2\cos ^2 \theta} \\
 &= \frac{\sec^2 \theta}{(C-1)\sec^2 \theta + 2} \\
&= \frac{\sec^2 \theta}{C + 1 + (C-1)\tan^2 \theta}
\end{align}
Hence 
\begin{align}
\int \frac{1}{C + \cos x} \text{d}x &= \int \frac{2}{C + \cos 2 \theta} d \theta \\
&= \int \frac{ 2\sec^2 \theta}{ C + 1 + (C-1)\tan^2 \theta} d \theta 
\end{align}
Now make the second substitution $t = \tan \theta$ and continue as above.
