Answer :
1. Given, Diameter and height of a cylinder are 42cm and 10cm. then r = 42/2 = 21
Then it's volume = πr²h = 22/7 × 21× 21× 10 = 13,860 cm³
2. volume of cylinder = πr²h = 3960
πr²h = 3960 => r²h = 3960 × 7/22
r²h = 1260 ---------- 1
csa of cylinder = 2πrh = 1320
2πrh = 1320 => rh = 1320 × 7/22×2
rh = 210
h = 210/r ---------------------2
by substituting in 1 we get r² × 210/r = 1260
r = 1260/210
r = 6 cm
then by substituting it in 2 we get h = 210/6
h = 35 cm
therefore radius(r) = 6 cm and height(h) = 35 cm
Then it's volume = πr²h = 22/7 × 21× 21× 10 = 13,860 cm³
2. volume of cylinder = πr²h = 3960
πr²h = 3960 => r²h = 3960 × 7/22
r²h = 1260 ---------- 1
csa of cylinder = 2πrh = 1320
2πrh = 1320 => rh = 1320 × 7/22×2
rh = 210
h = 210/r ---------------------2
by substituting in 1 we get r² × 210/r = 1260
r = 1260/210
r = 6 cm
then by substituting it in 2 we get h = 210/6
h = 35 cm
therefore radius(r) = 6 cm and height(h) = 35 cm