calculus
posted by Andrea .
How would you integrate tan5xdx ?
Thanks in advance.
Can you use u substitution?

try taking the derivative of
ln(cosx)
that should give you a good hint 
I know you get sin x; I know how to do the problem without the 5, but I don't understand how to do the problem since it is tangent of 5x

The derivative of ln(cosx) is actually
tanx, not sinx. "ln" means "natural (base e) logarithm of..
For the integral of tan 5x, let u = 5x
tan 5x = u
du = 5 dx
integral of tan(5x) dx
= integral of (1/5) tan u du
= (1/5)ln cos u
= (1/5)ln cos(5x)