Question

The curved surface area of a cylinder of height 21cm is 660cm square.find it's radius​

Answer 1

Answer: 5 cm

Step-by-step explanation:

Curved Surface area of a cylinder formula :- 2πrh (where r is the radius)

Height = 21 cm

Curved Surface area of the cylinder = 660 cm²

∴ 2πrh = 660 (Here I will assume π to be 22/7)

⇒  $2 * \frac{22}{7} * 21 * r$ = 660

⇒ $132 * r$ = 660

⇒  r = 660/132 = 5cm

Therefore radius of the cylinder = 5 cm

Answer 2

CSA=2πrh

660=2×(22/7)×r×21

r=(660×7)/(2×22×21)

r=4620/924

r=5cm

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