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Two concentric circles are drawn with radii 12 cm and 13 cm. What will be the length of any chord of the larger circle that is tangent to the smaller circle?
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- 5 cm
- 8 cm
- 10 cm
- 25 cm
- 5 cm
Correct Option: C
According to question , we draw a figure of two concentric circles with centre O 
AB is tangent at point C.
AC = BC
OA = 13 cm.
OC = 12 cm.
∠ACO = 90°
From ∆ OAC,
AC = √OA² - OC²
AC = √13² - 12²
AC = √(13 + 12)(13 -12) = √25 = 5 cm.
∴ AB = 2AC = 2 × 5 = 10 cm.
