# Trouble with some geometry

## Recommended Posts

dev578    128
I have two points, p1 and p2, and I know both of their coordinates. P2 is the center of a circle with radius x. Two tangent lines from the circle formed by p2 intersect at p1. I need to know the angle these two lines make. To clarify, if I made an arrow from p1 to p2, it would cross through the center of the angle I am looking for. I really do hate asking questions, but I don't really know how to research this one. Any help would be appreciated. Thank you, -dev578

##### Share on other sites
Zipster    2359
Draw the circle, the points, and the tangent lines. You know the tangent lines and the circle radius are at right angles, hence you have a right triangle (two actually but the problem is symmetrical so you only need to pick one). You also know two sides, the radius of the circle and the distance between P1 and P2. From there you should be able to use trigonometric identities to determine the angle.

##### Share on other sites
dev578    128
Oh, that was easy. Sorry, sometimes I overcomplicate things without seeing a simple solution. Thank you for your time.

-dev578