HOTS Mathematics Primary 6 Angles

In the figure, lines PQ and RS are parallel. A transversal cuts PQ at A and RS at B. The angle ∠QAB = 5x°. The angle ∠SBA = (3x + 60)°. ∠QAB and ∠SBA are co-interior angles. Find ∠QAB.

A 75°
B 127.5°
C 112.5°
D 105°
Show Worked Solution

Worked Solution

Step 1: Co-interior angles between two parallel lines sum to 180°. Step 2: 5x + (3x + 60) = 180 → 8x + 60 = 180 → 8x = 120 → x = 15. Step 3: ∠QAB = 5x = 5 × 15 = 75°. Answer: 75°

Correct answer: 75°

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