Problem 1 · 2024 Math Kangaroo
Medium
Geometry & Measurement
proportion
The angles in a triangle are in the ratio 1:3:5. What is the biggest of those angles?
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Answer: C — 100°
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Hint 1 of 2
The three parts of the ratio cover the whole 180° of the triangle.
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Hint 2 of 2
Add the ratio numbers to find how many equal shares there are, then take the biggest share.
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Approach: split 180° by the ratio
- The ratio 1:3:5 has 1+3+5 = 9 equal shares.
- Each share is 180° ÷ 9 = 20°.
- The biggest angle is 5 shares: 5 × 20° = 100°.
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