In the given figure, the diameter of a circle with center is perpendicular to chord If and calculate the radius of the circle.



Let radius OA = OC = OD = r


Chord AB = 12 cm


OE = OC – CE


OE = r – 3


AE = (1/2) AB


AE = (1/2) 12 = 6 cm


In triangle AOE,


OA2 = AE2 + OE2


r2 = 62 + (r - 3)2


r2 = 36 + r2 + 9 - 6r


6r = 45


r = 7.5 cm


Hence, radius of circle = 7.5 cm.


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