In triangle ABC, angle B is three times angle A, and angle C is 20° more than angle A. What is the size of angle B?
Answer and explanation
Correct answer: C. 96°
- Step 1: Let angle A = a, so B = 3a and C = a + 20. Step 2. a + 3a + a + 20 = 180, so 5a = 160 and a = 32. Step 3. B = 3 × 32 = 96°. Answer: 96°. Why not the others: 32°: This is the size of angle A. 52°: This is the size of angle C. 108°: This comes from forgetting the extra 20° when solving, so that 5a = 180°.
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