Two angles are supplementary. If one angle measures 65°, what is the measure of the other angle?
- A 25°
- B 35°
- C 115°
- D 295°
Check answer and explanation
Answer C: 115°
Supplementary angles sum to 180°: \(180-65=115°\).
CH06-06 lesson
Angle Relationships: Supplementary, Complementary, and Vertical Angles Learning Activity
A focused Grade 7 learning session for Angle Relationships: Supplementary, Complementary, and Vertical Angles using visual models, worked examples, strategy guidance, and a short mastery check.
- 15
- minutes
- 6
- lesson parts
- 11
- practice items
Students will build Grade 7 mastery of angle relationships: supplementary, complementary, and vertical angles using models, equations, and test-style reasoning.
Student goal: I can solve problems involving angle relationships: supplementary, complementary, and vertical angles.
Helpful first:
Cross-Sections of Three-Dimensional Figures
Learn the Idea
Angle Relationships: Supplementary, Complementary, and Vertical Angles is part of Grade 7 Geometry and Scale. This activity focuses on the central idea students need before they move into independent practice.
Students will build Grade 7 mastery of angle relationships: supplementary, complementary, and vertical angles using models, equations, and test-style reasoning.
See the Math
| What to notice | How to use it |
|---|---|
| Numbers, units, labels, diagrams, or graphs | Identify what each part represents before calculating. |
| The relationship in the problem | Connect the model to an equation, comparison, or explanation. |
Use the figures and worked questions in the practice set below as the visual model for this skill.
Follow a Worked Example
Read the first practice question slowly. Decide what the question is asking, choose a strategy, solve, and then compare your reasoning with the answer explanation.
For Angle Relationships: Supplementary, Complementary, and Vertical Angles, a strong worked example should show the setup, the calculation or model, and a final answer that matches the context.
Connect It to a Real Situation
Many Grade 7 test questions use real situations. Look for quantities, units, rates, measures, expressions, or data values that connect the math to the story.
After solving, explain what the answer means in the situation, not just the number you calculated.
Avoid Mistakes and Choose a Strategy
- Underline the exact question before solving.
- Label units, variables, or graph axes when they appear.
- Estimate first so unreasonable answers are easier to catch.
- Review missed questions and write the reason for each mistake.
Remember the Key Idea
I can solve problems involving angle relationships: supplementary, complementary, and vertical angles.
Use the warmup, guided question, practice set, and exit questions below to check whether this skill is ready or needs more practice.
Solve before opening the answer
Use scratch paper. The explanation matters more than simply seeing whether the choice is correct.
warmup
2 questionsTwo rays form a right angle, and a third ray splits it into complementary angles. One angle measures 34°. What is the measure of angle \(x\)?
- A 56°
- B 34°
- C 90°
- D 124°
Check answer and explanation
Answer A: 56°
Complementary angles sum to 90°: \(x=90-34=56°\).
guided
1 questionTwo straight lines intersect. One angle formed is 50°. What is the measure of the angle marked \(y\)?
- A 130°
- B 90°
- C 50°
- D 140°
Check answer and explanation
Answer A: 130°
Adjacent angles on a straight line are supplementary: \(y=180-50=130°\).
practice
5 questionsTwo lines intersect forming vertical angles. One angle is 72°. What is the measure of the vertically opposite angle \(a\)?
- A 18°
- B 72°
- C 108°
- D 180°
Check answer and explanation
Answer B: 72°
Vertical angles are equal, so the opposite angle is also 72°.
Two angles form a linear pair. One angle measures 91°. What is the measure of the other angle?
- A 1°
- B 89°
- C 45°
- D 179°
Check answer and explanation
Answer B: 89°
A linear pair is supplementary: \(180-91=89°\).
A ray splits a straight angle into two adjacent angles. One angle is 70°. Find the measure of angle \(b\).
- A 20°
- B 70°
- C 110°
- D 180°
Check answer and explanation
Answer C: 110°
Angles on a straight line are supplementary: \(180-70=110°\).
If angle \(x\) and angle \(y\) are complementary, and \(x=37°\), what is \(y\)?
- A 53°
- B 43°
- C 37°
- D 143°
Check answer and explanation
Answer A: 53°
Complementary angles sum to 90°: \(y=90-37=53°\).
Angle \(X\) is supplementary to an angle of 47°. What is the measure of angle \(X\)?
- A 133°
- B 93°
- C 43°
- D 227°
Check answer and explanation
Answer A: 133°
Supplementary angles sum to 180°: \(X=180-47=133°\).
exit
3 questionsTwo lines intersect. One angle measures 63°. What is the measure of the vertically opposite angle \(d\)?
- A 27°
- B 63°
- C 117°
- D 153°
Check answer and explanation
Answer B: 63°
Vertical angles are equal. The angle opposite 63° is 63°.
An angle measures 41°. What is the measure of its complementary angle?
- A 49°
- B 39°
- C 59°
- D 139°
Check answer and explanation
Answer A: 49°
Complementary angles sum to 90°: \(90-41=49°\).
A ray splits a straight angle into two adjacent angles. One angle is 45°. What is the measure of angle \(e\)?
- A 35°
- B 45°
- C 90°
- D 135°
Check answer and explanation
Answer D: 135°
Adjacent angles on a straight line are supplementary: \(e=180-45=135°\).
