HOTS Mathematics Primary 5 Angles

Wei Lin draws two parallel lines l1 and l2. A transversal crosses l1 at point P and l2 at point Q. She labels angle BPQ = (3y − 5)°, where B is on l1 to the right of P, and angle PQC = (2y + 15)°, where C is on l2 to the right of Q. She then draws segment PR to a point R on l2 such that R is to the right of Q and angle QPR = 28°. What is angle PRQ?

A 55°
B 69°
C 83°
D 111°
Show Worked Solution

Worked Solution

Step 1: Co-interior angles (same side of transversal PQ, between parallel lines). (3y − 5) + (2y + 15) = 180 5y + 10 = 180 y = 34 Step 2: angle PQC = 2(34) + 15 = 83° Step 3: R is on l2 to the right of Q, so angle PQR = angle PQC = 83°. Step 4: Triangle PQR angle sum. 28° + 83° + angle PRQ = 180° angle PRQ = 69°

Correct answer: 69°

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