F1e = the slope of tan.

The intersection of the root number (4e 2- 1) * (x+c) and the right branch of the equation y =1f1e can be solved by the root number y = b (x 2/a 2- 1).

(x+c)^2/(4e^2- 1)= b^2(x^2 /a^2- 1)