Skip to content
PlayOwl

Mathematics · Grade 10

Congruence and Rigid Motion

Learners define congruence through rigid motions, read congruence statements to find corresponding parts, and justify the triangle congruence criteria SSS, SAS, ASA, AAS and HL, including counterexamples showing why SSA and AAA fail. They plan and write two-column proofs of triangle congruence and then use congruent triangles (CPCTC) to prove further facts, such as the perpendicular bisector theorem.

  • 4 lessons
  • About 125 minutes
  • Congruence check: 11 questions
  • Ways to answer: fill in the blanks, choose an answer, highlight a text, match pairs, type a number and put in order
Try it now (no account) One of the five free starter courses Open in PlayOwl

What learners will discover

  • Define congruence using rigid motions and use a congruence statement to identify corresponding sides and angles.
  • Explain the triangle congruence criteria (SSS, SAS, ASA, AAS, HL) and show with counterexamples why SSA and AAA do not guarantee congruence.
  • Choose an appropriate criterion and write two-column and paragraph proofs that two triangles are congruent.
  • Use corresponding parts of congruent triangles (CPCTC) to prove segments or angles congruent, and detect flawed congruence arguments.

Lessons

  1. Congruence as rigid motion 6 steps4 practiceabout 28 min
  2. Triangle congruence criteria 7 steps4 practiceabout 32 min
  3. Writing congruence proofs 6 steps3 practiceabout 33 min
  4. CPCTC: using congruent triangles 6 steps4 practiceabout 32 min
  5. Congruence check 11 questions at the end

Keep exploring

More 10th grade math

Guide for grown-ups