Question

2. If the diameter of a cylinder
is 28 cm and its height is 20 cm,
then its curved surface area is​

Answer 1

Answer :

• The curved surface area of the cylinder is 1760 cm².

Explanation :

Given :

• Diameter of the cylinder = 28 cm

• Height of the cylinder = 20 cm

To find :

• Curved surface area of the cylinder , CSA = ?

Knowledge required :

• Diameter of a circle is the twice of it's radius i.e,

⠀⠀⠀⠀⠀⠀⠀⠀⠀Diameter = 2 × Radius

From the above equation, we get :

⠀⠀⠀⠀⠀⠀⠀⠀⠀Radius = Diameter/2

• Formula for Curved surface area of a cylinder :

⠀⠀⠀⠀⠀⠀⠀⠀⠀CSA = 2πrh

Where,

• CSA = Curved surface area
• r = Radius
• h = Height

Solution :

By using the formula for Curved surface area of a cylinder and by substituting the values in it , we get :

==> CSA = 2πrh

==> CSA = 2 × π × (D/2) × h ⠀⠀⠀⠀⠀⠀⠀[∴ R = D/2]

==> CSA = 2 × 22/7 = (D/2) × h ⠀⠀⠀⠀[∴ π = 22/7]

==> CSA = 2 × 22/7 × (28/2) × 20

==> CSA = 2 × 22/7 × 14 × 20

==> CSA = 2 × 22 × 2 × 20

==> CSA = 1760

∴ CSA = 1760 cm²

Therefore,

• The curved surface area of the cylinder is 1760 cm².

Answer 2

$\Large{\boxed{\underline{\overline{\mathfrak{\star \: QuEsTiOn :- \: \star}}}}}$

❥ If the diameter of a cylinder is 28 cm and its height is 20 cm, then its curved surface area is

$\Large{\underline{\underline{\bf{AnSweR:-}}}}$

$\large{\boxed{\bold{Curved\:Surface\:Area\:of\:Cylinder\:=\ 1760\:cm\:sq}}}$

$\Large{\underline{\underline{\bf{Given:-}}}}$

❥ Diameter (d) of Cylinder ↠ 28 cm

❥ Radius (r) of cylinder ↠ 14 cm

❥ Height (h) of Cylinder ↠ 20 cm

$\Large{\underline{\underline{\bf{To find :-}}}}$

❥ What is the Curved surface area of cylinder ?

$\Large{\underline{\underline{\bf{SoLuTioN :-}}}}$

✒ Curved Surface Area of Cylinder ↠2πrh

Where,

✒ Radius (r) ↠ 14 cm

✒ Height (h) ↠ 20 cm

Now ,

putting the values in the above formula

we get ,

➠ C.S.A  ↠ 2 × 22/7 14 × 20

➠ C.S.A  ↠ 2 × 22 × 2 × 20

➠ C.S.A  ↠ 4 × 22 × 20

➠ C.S.A  ↠ 1760 cm²

Hence ,

✒ The Curved Surface Area of Cylinder is

1760 cm².

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☛ Extra shots :-

• Volume of cone ↠1/3 πr²h

• Volume of sphere ↠4/3 πR³

• Volume of cube ↠ (Side)³

• Volume of cylinder ↠ πr²h

• Volume of Cone ↠ ⅓ × πr²h

• T.S.A of Cube ↠ 6 × (Side)²

• T.S.A of Cylinder ↠ 2πr² + 2πrh

• L.S.A of Cube ↠ 4 × (Side)²

• L.S.A of Cylinder ↠ 2πrh

• L.S.A of Cone ↠ πrl

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