So, I'm trying to solve this problem:

and I have x=7tan(theta)

dx=7(sec(theta))^2 d(theta)

Then

INTEGRAL 1/sqrt49+7(tan(theta))^2 * 7(sec(theta))^2 d(theta)

For that integral above, I'm thinking there's an identity to simplify that, but I'm not so sure how to... recognize it?