Problem preview
G-CO.11 Warmup M2-035-A09-V01

Prove parallelogram theorems and their converses, including diagonal and rectangle results.

Test the opposite-angles converse for a parallelogram

Problem

Decide whether the stated angle evidence is sufficient to prove a parallelogram: quadrilateral \(ABCD\) with \(\angle~A\cong~\angle~C\) and \(\angle~B\cong~\angle~D\).

Big Picture

What this problem is really about

A converse test requires the full hypothesis, so one matching angle pair cannot settle the classification. We’ll use cyclic vertex order to pair first with third and second with fourth, verify both opposite congruences, and only then apply the angle-based converse.

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Four variants of this problem type
Curriculum context
Course
Math II
Standard
G-CO.11
Category
Geometry
Domain
Congruence
Objective
Prove parallelogram theorems and their converses, including diagonal and rectangle results.
Problem type
Test the opposite-angles converse for a parallelogram