# HSG-CO.C.9

Prove theorems about lines and angles. Theorems include: vertical angles are congruent; when a transversal crosses parallel lines, alternate interior angles are congruent and corresponding angles are congruent; points on a perpendicular bisector of a line segment are exactly those equidistant from the segment's endpoints.

## Tasks

Tangent Lines and the Radius of a Circle

Points equidistant from two points in the plane

Congruent angles made by parallel lines and a transverse