So hmmm notice the picture below
recall the "inscribed angle" theorem, an angle inscribed is half the intercepted arc
now, the line BA goes through the center, and to each end, thus is a diameter, the point of tangency, where a tangent hits the diameter or radius of a circle, is always a right-angle
recall the "inscribed angle" theorem, an angle inscribed is half the intercepted arc
now, the line BA goes through the center, and to each end, thus is a diameter, the point of tangency, where a tangent hits the diameter or radius of a circle, is always a right-angle