- AComplementary angles
- BSupplementary angles
- CVertically opposite angles
- DAdjacent angles
Step-by-Step Solution
Two angles are complementary when their measures sum to 90°. Supplementary angles sum to 180°.
Answer: A) Complementary angles
Two angles whose measures add up to exactly 90° are called what?
Class 7Lines and AnglesLines and Angles
Key idea: Parallel lines and a transversal
When a transversal crosses two **parallel** lines, eight angles form (four at each intersection). They come in special pairs:
- **Corresponding angles**: same position at each intersection (e.g. both top-left). **Equal**.
- **Alternate interior angles**: between the parallel lines, on opposite sides of the transversal. **Equal**.
- **Alternate exterior angles**: outside the parallel lines, on opposite sides of the transversal. **Equal**.
- **Co-interior (same-side interior) angles**: between the parallel lines, on the same side of the transversal. **Supplementary** (sum to 180°).
These are the rules you'll use most. Sketch the figure and label what you know — the rest follows quickly.
- **Corresponding angles**: same position at each intersection (e.g. both top-left). **Equal**.
- **Alternate interior angles**: between the parallel lines, on opposite sides of the transversal. **Equal**.
- **Alternate exterior angles**: outside the parallel lines, on opposite sides of the transversal. **Equal**.
- **Co-interior (same-side interior) angles**: between the parallel lines, on the same side of the transversal. **Supplementary** (sum to 180°).
These are the rules you'll use most. Sketch the figure and label what you know — the rest follows quickly.
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More Class 7 Lines and Angles practice
Which of the following best describes a transversal?Can two acute angles be supplementary to each other?Can two obtuse angles be supplementary to each other?Two complementary angles are in the ratio 2 : 3. Find the smaller angle (in degrees).Two supplementary angles are in the ratio 4 : 5. Find the larger angle (in degrees).