A chord AB of circle C1 of radius 17 cm touches circle C2 which is concentric to C1. The radius of C2 is 8 cm. What is the length (in cm) of AB?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 30.
Chord AB acts as a tangent for circle C2.
In AOD,
OA2 = OD2 + AD2
172 = 82 + AD2
AD2 = 289 - 64 = 225
AD = 15
AB = 2 × AD
AB = 2 × 15 = 30 cm.