Q1) Find the surface area of sphere whose diameter is
a) 20 cm
b) 30 cm
c) 45 m
Ans a)
Surface area of sphere= 4πr²
As diameter is 20 cm hence radius will be 10 cm ( r=d/2)
Therefore
Area = 4×22/7*10*10
= 4×3.1428*100
= 12.5714*100
= 1257.14 cm²
Ans b)
Surface area of sphere= 4πr²
As diameter is 30 cm hence radius will be 15 cm ( r=d/2)
Therefore
Area = 4×22/7*15*15
= 4×3.1428*
= 12.5714*225
= 2828.52 cm²
Ans c)
Surface area of sphere= 4πr²
As diameter is 45m hence radius will be 22.5 m ( r=d/2)
Therefore
Area = 4×22/7*22.5*22.5
= 4×3.1428*506.25
= 12.5714*506.25
= 6364.17m²
