Try This - For the given image, name the 2 tangent lines and the points of tangency For the given image, name the 2 tangent lines and the 3 points of tangency. Tangent lines: Points of tangency: EXPLAIN 1 Proving the Tangent-Radius Theorem Read the section below and complete the following activity (adapted from Lesson 15.3). Tangent-Radius Theorem If a line is tangent to a circle, then it is perpendicular to a radius drawn to the point of tangency.