a

the angle between a tangent and a radius drawn at the point of contact is a right angle.

  • a rough proof by contradiction: - a rough proof by contradicton: - assume line is tangent to the circle at C but - what is loss of generality? - without loss of generality, we assume is acute the angle between a tangent and chord equals the angle in the alternate segment the two tangents drawn form a point to a circle are of equal length