Radius of two concentric circles are 4 cm and 3 cm respectively. Then

1.	Radius of two concentric circles are 4 cm and 3 cm respectively. Then area bounded by these circles will be:(A) 22 cm2(B) 12 cm2(C) 32 cm2(D) 18 cm2
Answer» Answer is (A) 22 cm² Given : Radius of two concentre circle are 4 cm and 3 cm. Thus, R= 4 cm, r = 3 cm ∴ Area between two concentric circles = π(R² – r²) = \(\frac { 22 }{ 7 }\) [(4)² – (3)²] = \(\frac { 22 }{ 7 }\) × [(4 + 3) (4 – 3)] = \(\frac { 22 }{ 7 }\) × 7 = 22 cm²

Radius of two concentric circles are 4 cm and 3 cm respectively. Then area bounded by these circles will be:(A) 22 cm2(B) 12 cm2(C) 32 cm2(D) 18 cm2

Answer»

Answer is (A) 22 cm²

Given : Radius of two concentre circle are 4 cm and 3 cm.

Thus, R= 4 cm, r = 3 cm

∴ Area between two concentric circles

= π(R² – r²)

= \(\frac { 22 }{ 7 }\) [(4)² – (3)²]

= \(\frac { 22 }{ 7 }\) × [(4 + 3) (4 – 3)]

= \(\frac { 22 }{ 7 }\) × 7 = 22 cm²