Question

How i cam solve this
very easily
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Answer 1

Let O be the centre of the concentric circle of radii 5 cm and 3 cm respectively. Let AB be a chord of the larger circle touching the smaller circle at P.

Then

AP=PB and OP⊥AB

Applying Pythagoras theorem in △OPA, we have

OA 2 =OP 2 +AP 2

⇒25=9+AP 2

⇒AP 2 =16⇒AP=4 cm

∴AB=2AP=8 cm

Answer 2

Let O be the centre of the concentric circle of radii 5 cm and 3 cm respectively. Let AB be a chord of the larger circle touching the smaller circle at P.

Then

AP=PB and OP⊥AB

Applying Pythagoras theorem in △OPA, we have

OA 2 =OP 2 +AP 2

⇒25=9+AP 2

⇒AP 2 =16⇒AP=4 cm

∴AB=2AP=8 cm