High School · Congruence

CCSS.MATH.CONTENT.HSG.CO.A.1

Know precise definitions of angle, circle, perpendicular line, parallel line, and line segment, based on the undefined notions of point, line, distance along a line, and distance around a circular arc.

Read this standard on the official Common Core site

Lessons that teach this standard

• Two-Column Proofs: Lines, Angles and Perpendicular Bisectors

  How a geometry proof is built from definitions, postulates and earlier theorems, with complete proofs about vertical angles, parallel lines and perpendicular bisectors.