In two concentric circles the radius of inner is 5 cm a chord of length 24 m of outer circle becomes a tangent to the inner circle. Find the radius of the larger circle.
Let O be the centre of circle and AB be the chord OT is radius of smaller circle
So OTAB since tangent is to radius at its point of contact.
AT = TB = 12 cm
(since perpendicular from centre to the chord bisects it)
So, In triangle OAT,
OA2 = OT2 + AT2
OA2 = 52 + 122
So, OA = 13 cm
Thus, the radius of the larger circle is 13 cm.
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