Tangents which meet at the same point are the same length, so with the chord they form an isosceles triangle. Angles in a triangle add up to 180°. \(c = 180^\circ - 65^\circ - 65^\circ = 50^\circ\) ...

A tangent to a circle is perpendicular to the radius which meets the tangent. which meet at the same point are the same length. Angles in a triangle add up to 180°. \(c = 180 - 65 - 65 = 50^\circ\) ...