Geometry worksheet illustrating various angle types with definitions and examples.

Let’s go step by step to fill in the blanks correctly. We’ll use basic angle definitions and properties.

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1. An acute angle measures ______.
→ Acute angles are less than 90°.
✔ Answer: less than 90°

2. An obtuse angle measures ______.
→ Obtuse angles are more than 90° but less than 180°.
✔ Answer: more than 90° but less than 180°

3. A right angle measures ______.
→ Right angle is exactly 90°.
✔ Answer: exactly 90°

4. A straight angle measures ______.
→ Straight angle is a straight line — 180°.
✔ Answer: exactly 180°

5. Complementary angles ______.
→ Two angles that add up to 90°.
✔ Answer: add up to 90°

6. Supplementary angles ______.
→ Two angles that add up to 180°.
✔ Answer: add up to 180°

7. Congruent angles ______.
→ Angles with the same measure.
✔ Answer: have the same measure

8. Two adjacent angles are a linear pair when ______.
→ They are next to each other AND form a straight line (so they’re supplementary).
✔ Answer: they are adjacent and their non-common sides form a straight line (or they add up to 180°)

9. Vertical angles ______.
→ Opposite angles formed by two intersecting lines — always equal.
✔ Answer: are opposite each other when two lines cross and are always equal

10. Adjacent angles ______.
→ Share a common side and vertex, no overlap.
✔ Answer: share a common side and vertex but do not overlap

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Now let’s match these to the grid on the right. The grid has labels like “Obtuse”, “Acute”, etc., and we need to place the correct definition or property under each.

Looking at the grid:

Row 1:
- Left: “Obtuse” → should have: *measures more than 90° but less than 180°*
- Right: “Acute” → *measures less than 90°*

Row 2:
- Left: “Straight” → *measures exactly 180°*
- Right: “Right” → *measures exactly 90°*

Row 3:
- Left: “Supplementary” → *angles that add up to 180°*
- Right: “Complementary” → *angles that add up to 90°*

Row 4:
- Left: “Linear Pair” → *two adjacent angles whose non-common sides form a straight line (sum = 180°)*
- Right: “Congruent” → *angles that have the same measure*

Row 5:
- Left: “Adjacent” → *angles that share a common side and vertex, no overlap*
- Right: “Vertical” → *opposite angles formed by intersecting lines; always equal*

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Final Answer:

An acute angle measures less than 90°.
An obtuse angle measures more than 90° but less than 180°.
A right angle measures exactly 90°.
A straight angle measures exactly 180°.
Complementary angles add up to 90°.
Supplementary angles add up to 180°.
Congruent angles have the same measure.
Two adjacent angles are a linear pair when they are adjacent and their non-common sides form a straight line (or they add up to 180°).
Vertical angles are opposite each other when two lines cross and are always equal.
Adjacent angles share a common side and vertex but do not overlap.

For the grid on the right, fill each box as follows:

- Under “Obtuse”: *measures more than 90° but less than 180°*
- Under “Acute”: *measures less than 90°*
- Under “Straight”: *measures exactly 180°*
- Under “Right”: *measures exactly 90°*
- Under “Supplementary”: *angles that add up to 180°*
- Under “Complementary”: *angles that add up to 90°*
- Under “Linear Pair”: *two adjacent angles whose non-common sides form a straight line*
- Under “Congruent”: *angles that have the same measure*
- Under “Adjacent”: *angles that share a common side and vertex, no overlap*
- Under “Vertical”: *opposite angles formed by intersecting lines; always equal*