Advanced Mathematics Primary 5 Geometry

In triangle PQR, PQ = PR and angle QPR = 48°. The side QR is extended beyond R to a point S. Find angle PRS.

A 48°
B 66°
C 114°
D 132°
Show Worked Solution

Worked Solution

Step 1: Use the isosceles triangle property. Since PQ = PR, the base angles are equal. Angle PQR = Angle PRQ Step 2: Apply the angle sum of a triangle. Angle PQR + Angle PRQ + Angle QPR = 180° 2 × Angle PRQ + 48° = 180° 2 × Angle PRQ = 132° Angle PRQ = 66° Step 3: Use the angles-on-a-straight-line property. QR extended to S means PRQ and PRS are supplementary. Angle PRS = 180° − 66° = 114° Answer: Angle PRS = 114° Answer: 114°

Correct answer: 114°

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