Find a tangent point on circle?

Question

Given a line with first end point P(x1,y1) another end point is unknown, intersect with a circle that located at origin with radius R at only one point(tangent) T(x2,y2). Anyone know how to get the point T? Thanks in advance!

Answer 1

Since it tangent to the circle, then the radius will be perpendicular to the line at (x₂,y₂), so you've got a right triangle with the radius perpendicular to the line with point P on it.T is the 90° angle.