Let γ : R → R2 be the plane curve given by γ(t) = (3 tanh t, 2 sech t). Show that the

image of γ is contained in an ellipse, and determine the equation of the ellipse. Is the

image the whole ellipse?

I can't work out where to start, the only thing I can think is that I have to use tanh^2 x + sech^2 x =1, but I'm not sure how ?!