The integral of ln(1+x) tan(x) with respect to x can be calculated using integration by parts. The integration by parts formula states:

∫ u dv = uv – ∫ v du

Let’s denote u = ln(1+x) and dv = tan(x) dx. Then, we can differentiate u to get du and integrate dv to get v. Here’s the breakdown:

u = ln(1+x) du = (1 / (1+x)) dx

dv = tan(x) dx v = -ln|cos(x)| + C, where C is the constant of integration

Now, applying the integration by parts formula:

∫ ln(1+x) tan(x) dx = uv – ∫ v du = ln(1+x) (-ln|cos(x)|) + ∫ (-ln|cos(x)|) (1 / (1+x)) dx

The last integral on the right side can be quite challenging to integrate further, and it might not have a simple closed form. This is a common scenario in integration, where some integrals do not have elementary solutions.

So, the integral of ln(1+x) tan(x) with respect to x is:

∫ ln(1+x) tan(x) dx = ln(1+x) (-ln|cos(x)|) + ∫ (-ln|cos(x)|) (1 / (1+x)) dx

If you have specific limits of integration, you can apply these limits to the integral to evaluate it numerically.