Question

1]Diameter and height of a cylinder are 42cm and 10cm.Find it's volume
2]the volume of a cylinder is 3960cm[cube].Its curved surface area is 1320cm[square].Find the radius of base and height of cylinder.

PLz its urgent

Answer 1

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