Foundation Mathematics Primary 5 Angles

Two straight lines AB and CD cross at point O on a school field marker. The angle ∠AOC = 72°. Find the size of ∠BOD, the angle directly opposite ∠AOC.

A 18°
B 72°
C 108°
D 144°
Show Worked Solution

Worked Solution

Step 1: Identify the angle relationship. ∠AOC and ∠BOD are formed by the same two lines crossing at O on opposite sides — they are VERTICALLY OPPOSITE angles. Step 2: Vertically opposite angles are EQUAL. Therefore ∠BOD = ∠AOC = 72°. Final answer: ∠BOD = 72°. Answer: 72°

Correct answer: 72°

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