Question

if the difference between inner and outer radii of a hollow ring is 21cm and the surface area of the hollow ring is 6600 cm^2. then what are the radii of the outer and inner circles of the hollow ring? ​

Answer 1

Answer:

let outer radius be R and inner radius be r.

R-r=21 cm. -(1)

Surface area=pi(R^2-r^2)

6600=22/7(R+r)(R-r)

300=1/7(R+r)×21

300=(R+r)×3

100=R+r -(2)

By adding 1 and 2,

2R=121

R=121/2=60.5 cm

r=38.5 cm.

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