HOTS Mathematics Primary 6 Angles

In a triangle, one angle is twice another angle. The third angle is 60°. What are the two unknown angles?

A 30° and 90°
B 40° and 80°
C 50° and 70°
D 60° and 60°
Show Worked Solution

Worked Solution

Step 1: Let the smaller angle = x. Then the larger = 2x. Step 2: x + 2x + 60° = 180°. So 3x = 120°, x = 40°. Step 3: The two angles are 40° and 2 × 40° = 80°. Step 4: Check: 40 + 80 + 60 = 180. ✓ Answer: 40° and 80°

Correct answer: 40° and 80°

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