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‘O’ is the centre of the circle, AB is a chord of the circle, OM ⊥ AB. If AB = 20 cm, OM = 2 11 cm, then radius of the cir-cle is
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- 15 cm
- 12 cm
- 10 cm
- 11 cm
- 15 cm
Correct Option: B
According to question , we draw a figure of a circle with centre O , 
AB = 20 cm.
AM = MB = 10 cm.
From ∆ AOM ,
OM = 2 √11 cm.
∴ Radius OA = √OM² + AM²
OA = √(2√11)² + 10²
OA = √4 × 11 + 100
OA = √44 + 100
OA = √144 = 12 cm.
