Finding Missing Angles
Grade 9th Grade · Math · 45 min
What's Included
Learning Objective
I can calculate the measure of an unknown angle that is supplementary to a known angle.
Warm-Up Video
Kayla Jones · 3:17
Supplementary Angles
Guided Notes
3 key concepts
- 1
Supplementary angles are two or more angles that add up to 180 degrees.
- 2
If two angles are supplementary, you can set up an equation where the sum of the angles equals 180° and then solve for the unknown angle.
- 3
When parallel lines are cut by a transversal, angles on a flat line are supplementary, meaning their measures add up to 180 degrees, allowing you to solve for variables like x.
Practice Questions
11 questions · Multiple choice & Short answer
Exit Ticket
Quick comprehension check
“Angle A and angle B are supplementary angles. If the measure of angle A is 123°, what is the measure of angle B?”
Teacher Guide
Get the complete package:
- Answer keys for all questions
- Differentiation strategies
- Extension activities
- Printable student handouts
