Problem preview
G-CO.9 Warmup M2-036-A12-V01

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

Combine line, angle, and perpendicular-bisector facts in a multi-step problem

Problem

Angle \(A\) measures \(65^{\circ}\), and angle \(B\) is vertical to angle \(A\). What is the measure of angle \(B\)?

Big Picture

What this problem is really about

At an intersection, the directly opposite region uses equality while an adjacent region uses a supplementary relationship. We’ll locate the requested angle relative to the given one, classify the pair before doing arithmetic, transfer the measure through congruence, and distinguish the unused linear-pair value.

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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
Combine line, angle, and perpendicular-bisector facts in a multi-step problem