Problem preview
G-CO.9 Warmup M2-036-A05-V01

Prove theorems about lines and angles: vertical angles, parallel-line angle relationships, and perpendicular bisectors.

Use alternate exterior angles with parallel lines

Problem

Given alternate exterior angles with \(\text{one}~\text{angle}\) \(115^{\circ}\), use alternate exterior angles to find the missing angle measure.

Big Picture

What this problem is really about

For alternate-exterior angles, both regions must be outside the parallel lines and on opposite sides of the transversal. We’ll confirm those two position tests, use the congruent-angle relationship, and check that the unused supplement belongs to an adjacent region instead.

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Four variants of this problem type
Curriculum context
Course
Math II
Standard
G-CO.9
Category
Geometry
Domain
Congruence
Objective
Prove theorems about lines and angles: vertical angles, parallel-line angle relationships, and perpendicular bisectors.
Problem type
Use alternate exterior angles with parallel lines