Question

4. The surface area of a sphere and curved
surface area of a hemisphere are equal. Find
the ratio of their radii.​

Answer 1

Answer:

surface area of sphere=4πR²

curved surface area of hemisphere=2πr²

therefore

4πR²=2πr²

R²/r²=2π/4π

R²/r²=1/2

R/r=√(1/2)

R/r=1/√2

therefore

ratio of radius of sphere: ratio of radius of hemisphere=1:√2