Foundation Mathematics Primary 5 Angles

Three rays leave a single point O on a Singapore Discovery Centre signpost, dividing the full turn around O into three angles of 130°, 110°, and ∠a. Find the size of ∠a.

A 50°
B 120°
C 240°
D 250°
Show Worked Solution

Worked Solution

Step 1: Recall the rule — angles at a point add up to 360°. Step 2: Write the equation: 130° + 110° + ∠a = 360°. Step 3: Add the two known angles: 130° + 110° = 240°. Then ∠a = 360° − 240° = 120°. Final answer: ∠a = 120°. Answer: 120°

Correct answer: 120°

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