Two concentric circles are of radii 15 cm and 6 cm. Whatis the length (in cm) of the chord ofthe larger circle that is tangent to the smaller circle?
Answer & explanation
Correct answer: option 1
We have,
AO = 15 cm and OC = 6 cm
According to the Pythagoras theorem,
AC2 = AO2 - OC2
= AC2 = 152 - 62
= AC2 = 225 - 36
= AC2 = 189
= AC = $3\sqrt{21}$
AB = 2AC = 2 x $3\sqrt{21}$ = $6\sqrt{21}$ cm