📚 Topic Summary
Measuring angles is a fundamental skill in geometry. A protractor is the primary tool used to measure angles in degrees. To measure an angle, place the center point of the protractor on the vertex of the angle and align the base line (0° line) with one side of the angle. Read the degree measurement where the other side of the angle intersects the protractor scale. Remember that angles can be acute (less than 90°), right (exactly 90°), obtuse (greater than 90° and less than 180°), straight (exactly 180°), or reflex (greater than 180°).
📐 Part A: Vocabulary
Match the term with the correct definition:
| Term |
Definition |
| 1. Acute Angle |
A. An angle greater than 90° and less than 180° |
| 2. Obtuse Angle |
B. The point where two lines meet to form an angle |
| 3. Right Angle |
C. An angle that measures exactly 90° |
| 4. Vertex |
D. An angle less than 90° |
| 5. Straight Angle |
E. An angle that measures exactly 180° |
✍️ Part B: Fill in the Blanks
Complete the following paragraph using the words: protractor, degrees, vertex, angle, base line.
To measure an __________, you will need a __________. Place the center of the protractor on the __________ of the angle. Align the __________ with one side of the angle. The angle is measured in __________.
🤔 Part C: Critical Thinking
Explain in your own words why it is important to accurately align the protractor's base line when measuring an angle.