Integrate tan(x)^2 with respect to x

sin(x)2 + cos(x)2 = 1 divide by cos(x)2 tan(x)2 + 1 = sec(x)2 therefore tan(x)2 = sec(x)2 - 1 integral of sec(x)2 - 1 rwt x = tan(x) - x + C therefore the integral of tan(x)2 rwt x = tan(x) - x + C