*Learning Goal: Assess conceptual understanding and procedural fluency for properties of parallelograms.*

# Classwork

- Concept Quiz
- 100 level question taken from Open Middle

- Retake: Triangle Congruence Proofs
- 100 level question taken from John O’Malley IV

# Finished Early?

# Standards

**Common Core**- HSG.CO.C.11 – Prove theorems about parallelograms. Theorems include: opposite sides are congruent, opposite angles are congruent, the diagonals of a parallelogram bisect each other, and conversely, rectangles are parallelograms with congruent diagonals.

**TEKS**- G.5(A) – investigate patterns to make conjectures about geometric relationships, including angles formed by parallel lines cut by a transversal, criteria required for triangle congruence, special segments of triangles, diagonals of quadrilaterals, interior and exterior angles of polygons, and special segments and angles of circles choosing from a variety of tools

I’m having trouble finding an answer for the 100 Level Question on the Triangle Proofs Retake. Help please 🙂

Hey Denise. I’m actually having trouble as well. I’m thinking angles 3 and 4 can be proven congruent with something like the angle addition postulate, but I’m not sure how to get there yet.

What if we went ahead and added to the given information that angle 3 is congruent to angle 4? Would that make it too easy for 100 level? Here’s my rough sketch of a solution for the problem with that information added.

Hey Denise. I figured out the issue. Turns out, I didn’t create a correct diagram. Angles 3 and 4 should have been drawn as vertical angles. The image is updated now, and here’s an answer key from John O’Malley IV, the original creator of the problem.