Hey, im new here, got a quick conics question. Im not sure if it really belongs here but it still is high school maths. Anyway..

The line y = mx + c is a tangent to the hyperbola x^2/25 - y^2/16 = 1. Show that c^2 = 25m^2 - 16.Done this bit

The tangents from P(x1, y1) to this hyperbola meet at right angles. Prove that the locus of P is the circle x^2 + y^2 = 9