- A180
- B99
- C81
- D90
Step-by-Step Solution
Angle A + angle B = 180 (adjacent). Half-angles: angle OAB + angle OBA = 90. In triangle AOB, angle AOB = 180 - 90 = 90°.
Answer: D) 90
Bisectors of angle A and angle B of parallelogram ABCD meet at point O.
Using the adjacent-angle property, find angle AOB (in degrees).
Class 9Conditions for a ParallelogramGeometry — Quadrilaterals
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