Exercises: Prove Theorems About Triangles

Work through each section in order. Show your reasoning for proof-based problems.

Grade 9·21 problems·~35 min·Common Core Math - HS Geometry·standard·hsg-co-c-10

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Warm-Up: Review What You Know

These problems review skills you already have.

Lines $\ell$ and $m$ are parallel, cut by a transversal $t$ . Which theorem guarantees that the alternate interior angles are congruent?

Vertical Angles Theorem

Alternate Interior Angles Theorem

Corresponding Angles Postulate

Same-Side Interior Angles Theorem