Question

A RIGHT CIRCULAR CYLINDER CIRCUMSCRIBES OF A SPHERE OF RADIUS r.FIND THE RATIO OF THEIR SURFACE AREA TO CSA OF THE CYLINDER

Answer 1

Surface area of sphere = 4πr²

Height of cylinder = r + r = 2r

Radius of cylinder = r

CSA of cylinder = 2πrh

= 2πr (2r)

= 4πr²

(iii)Ratio=4$\pi$r²/4$\pi$r²

Therefore, the ratio between these two surface areas is 1:1.

Answer 2

Ratio of surface area of cylinder to CSA of cylinder is:-

Surface area/ CSA = 2πr(h+r) / 2πrh

Therefore, 2πr and 2πr of both the side will be cut

Therefore,
Surface area: CSA = h+r:h