Geometrymedium · Past Paper
In the given figure, O is the center. If angle OAB = 30 degrees, find angle ACB.
A30 degrees
B60 degrees
C120 degrees
D150 degrees
✓ Correct Answer: B — 60 degrees
Triangle OAB is isosceles (OA=OB), so angle OBA=30. Angle AOB = 180 - 60 = 120. Angle ACB = 120/2 = 60 degrees.
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