First you need the equation for your line. You have two points, so find the slope and intercept of your line from this. Next, you know that this line intersects with your circle at some point (x, y). You have two equations: and . You know m and b so put the y value from your line into the circle formula.

Those are the general steps. See what you can do from here and let us know what, if any, problems you are having.

-Dan