I have another seperation by variables problem, and the hardest part for me is separating the variables which is probably why we have this lesson.

This one seems complicated..I have to solve this dif eq by using sep. by variables:

y dy = t(1 + t^2)^(-1/2) * (1 + y^2)^(1/2) dt

The square root in the denominator for t and the square root in the numerator for y seems hard to separate them.