HOTS Mathematics Primary 4 Angles

In the figure, OA, OB, OC and OD are four rays from point O. Angle AOB = angle COD = 35°. Angle BOC = 2 × angle AOB. Angle DOA (going the remaining way round) completes the full turn. What is the size of angle DOA (the reflex path)?

A 220°
B 225°
C 230°
D 255°
Show Worked Solution

Worked Solution

Step 1: Angle BOC = 2 × angle AOB = 2 × 35° = 70°. Step 2: Sum of known angles = angle AOB + angle BOC + angle COD = 35° + 70° + 35° = 140°. Step 3: Reflex angle DOA = 360° − 140° = 220°. Check: 35 + 70 + 35 + 220 = 360. ✓

Correct answer: 220°

Want more questions like this? Superholic Lab has 10,000+ MOE-aligned questions with full worked solutions.

Start Free Trial — 7 Days Free