Let's solve the problem step by step.
We are given five images showing a protractor with angles drawn on it. The task is to
measure each angle using the protractor and write the measurement in the box (though there are no boxes shown here, we will just provide the measurements).
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🔍 How to read a protractor:
- The protractor has two scales:
inner and
outer, going from 0° to 180° in both directions.
- Always align the
vertex of the angle with the center of the protractor.
- Align one side of the angle with the
0° line (either the left or right).
- Then read the angle where the other side crosses the scale.
- Use the correct scale based on which direction the angle opens.
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Let’s analyze each diagram:
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🟦 Top Left Angle
- One ray is along the
0° mark (right side).
- The other ray points to
130° on the
outer scale.
- Since the angle opens
counterclockwise, we use the outer scale.
-
✔ Measurement: 130°
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🟦 Top Right Angle
- One ray is along the
0° mark (right side).
- The other ray points to
70° on the
outer scale.
- Opens counterclockwise → outer scale.
-
✔ Measurement: 70°
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🟦 Middle Left Angle
- One ray is along the
0° mark (left side) — so we’re using the
inner scale.
- The other ray points to
80° on the inner scale.
- Opens clockwise → inner scale.
-
✔ Measurement: 80°
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🟦 Middle Right Angle
- One ray is along the
0° mark (left side), so use
inner scale.
- The other ray points to
150° on the inner scale.
-
✔ Measurement: 150°
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🟦 Bottom Angle (Two rays forming a V)
- This one has
two rays extending from the center.
- One ray points to
40° on the
inner scale (left side).
- The other ray points to
140° on the
outer scale (right side).
- But since both rays originate from the same point, this forms an angle between them.
- We can measure the angle between the two rays directly.
- From
40° to 140°, the difference is:
$140° - 40° = 100°$
- Alternatively, you could see that the angle spans from 40° to 140° across the center.
-
✔ Measurement: 100°
> Note: If you're measuring the angle at the vertex between the two red lines, it's the smaller angle formed, which is 100°.
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✔ Final Answers:
1. Top Left:
130°
2. Top Right:
70°
3. Middle Left:
80°
4. Middle Right:
150°
5. Bottom:
100°
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Let me know if you'd like these written in a box format or need help drawing similar angles!
Parent Tip: Review the logic above to help your child master the concept of measuring angle worksheet 4th grade.
