Two concentric ci

Given the radius of larger circle = 73 = OB and radius of smaller circle = 55 = OM

Since AB is a tangent, OM ⊥ AB.

Consider ΔOMB,

Here, ∠OMB is a right angle.

By Pythagoras Theorem,

⇒ OB² = OM² + MB²

⇒ MB² = OB² – OM²

= 73² – 55²

We know that a² – b² = (a + b) (a – b)

⇒ MB² = (73 + 55) (73 – 55)

= (128) (18)

= 2304

∴ MB = 48

Now, length of chord = AB = 2MB = 2 (48) = 96

∴ The length of chord is 96.