Question

If curved surface area of a cylinder is 1320 sq cm and height is 10 cm, find its radius?

A) 21 cm B) 42 cm C) 63 cm D) 10.5 cm

Answer 1

Given :

• Curved surface area of a cylinder is 1320 sq cm.
• Height of the cylinder = 10 cm.

To find :

• It's radius =?

Formula Used :

• Curved surface area of a cylinder = 2πrh.

Step-by-step explanation :

It is Given that,

Curved surface area of a cylinder is 1320 sq cm.

As We know that,

Curved surface area of a cylinder = 2πrh.

Substituting the values in the above formula, we get,

1320 = 2 × π × r × 10

20πr = 1320

πr = 1320/20

πr = 66

r = 66 ÷ (22/7) [ π = 22/7]

r = 66 × 7/22

r = 462/22

r = 21.

Therefore, Radius of the cylinder = 21 cm.

Hence, Option a). 21 cm is the correct option.

Answer 2

✯✯ QUESTION ✯✯

If curved surface area of a cylinder is 1320 sq cm and height is 10 cm, find its radius?

A) 21 cm B) 42 cm C) 63 cm D) 10.5 cm

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✰✰ ANSWER ✰✰

• C.S.A of Cylinder = 1320cm²
• Height ( h ) of Cylinder = 10cm
• Radius ( r ) of Cylinder = ?

➥Using Formula : -

$\longmapsto\tt{\large{\boxed{\bold{\bold{\red{\sf{C.S.A\:of\:Cylinder=2\pi{rh}}}}}}}}$

➥Putting Values : -

$\longmapsto\tt{1320=2\times\dfrac{22}{7}\times{r}\times{10}}$

$\longmapsto\tt{1320\times{7}=2\times{22}\times{10}\times{r}}$

$\longmapsto\tt{9240=440r}$

$\longmapsto\tt{r=\cancel\dfrac{9240}{440}}$

$\pink\longmapsto\:\large\underline{\boxed{\bf\red{r}\green{=}\orange{21\:cm}}}$

☛So , The radius of Cylinder is 21cm..

✔Option A) 21 cm is Correct..