It looks like you've uploaded a worksheet titled
"Calculating Missing Angles on a Straight Line", which contains several problems where students must find missing angles that form a straight line.
Key Concept:
Angles on a
straight line add up to
180°.
So, if you're given one or more angles on a straight line, you can find the missing angle(s) by subtracting the known angles from 180°.
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Let’s go through each problem in the worksheet (based on the visible diagrams). I'll solve them step by step and explain the reasoning.
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Problem 1:
- Given: One angle = 50°
- Find: Missing angle
Solution:
Since angles on a straight line sum to 180°:
Missing angle = 180° – 50° =
130°
✔ Answer:
130°
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Problem 2:
- Given: One angle = 30°
- Find: Missing angle
Solution:
Missing angle = 180° – 30° =
150°
✔ Answer:
150°
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Problem 3:
- Given: One angle = 60°
- Find: Missing angle
Solution:
Missing angle = 180° – 60° =
120°
✔ Answer:
120°
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Problem 4:
- Given: Two angles: 75° and 40°
- Find: Missing angle
Solution:
Sum of known angles = 75° + 40° = 115°
Missing angle = 180° – 115° =
65°
✔ Answer:
65°
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Problem 5:
- Given: One angle = 100°
- Find: Missing angle
Solution:
Missing angle = 180° – 100° =
80°
✔ Answer:
80°
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Problem 6:
- Given: One angle = 35°
- Find: Missing angle
Solution:
Missing angle = 180° – 35° =
145°
✔ Answer:
145°
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Problem 7:
- Given: One angle = 90°
- Find: Missing angle
Solution:
Missing angle = 180° – 90° =
90°
✔ Answer:
90°
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Problem 8:
- Given: Two angles: 50° and 40°
- Find: Missing angle
Solution:
Sum of known angles = 50° + 40° = 90°
Missing angle = 180° – 90° =
90°
✔ Answer:
90°
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Problem 9:
- Given: Three angles: 50°, 40°, and 35°
- Find: Missing angle
Solution:
Sum of known angles = 50° + 40° + 35° = 125°
Missing angle = 180° – 125° =
55°
✔ Answer:
55°
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Summary of Answers:
| Problem | Missing Angle |
|--------|----------------|
| 1 | 130° |
| 2 | 150° |
| 3 | 120° |
| 4 | 65° |
| 5 | 80° |
| 6 | 145° |
| 7 | 90° |
| 8 | 90° |
| 9 | 55° |
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Explanation:
All these problems use the
straight line angle rule:
> The sum of angles on a straight line is always
180°.
So, whenever you see two or more angles forming a straight line, just add the known angles and subtract from 180° to find the missing one.
This concept is fundamental in geometry and helps build understanding for more complex shapes and angle relationships.
Let me know if you'd like this explained visually or want a printable version!
Parent Tip: Review the logic above to help your child master the concept of calculating angles worksheet.
