1.

The curved surface area of a sphere of radius 5, intercepted between two parallel planes of distance 2 and 4 from the centre is …(a) 20π(b) 40π (c) 10π (d) 30π

Answer»

(a) 20π

The curved surface area of a sphere of radius r intercepted between two parallel planes at a distance a and b from the centre of the sphere is 2πr (b – a) 

Given radius, r = 5; a = 2; b = 4 

Required surface area = 2πr (b – a) 

= 2π × 5 × (4 – 2) 

= 20π sq. units



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