Question

The Radius of a right circular cylinder is 7 cm and it's hieght is 20cm .find its curved surface area and total surface area​

Answer 1

Answer:

Given :-

• The radius of a right circular cylinder is 7 cm and its height is 20 cm.

To Find :-

• What is the curved surface area and total surface area of cylinder.

Solution :-

☆ Curved Surface Area or CSA Of Cylinder :

Given :

• Radius = 7 cm
• Height = 20 cm

According to the question by using the formula we get,

$\bigstar \: \: \sf\boxed{\bold{\pink{C.S.A_{(Cylinder)} =\: 2{\pi}rh}}}\: \: \: \bigstar$

where,

• C.S.A = Curved Surface Area
• π = Pie or 22/7
• r = Radius
• h = Height

By putting the values we get,

$\implies \sf C.S.A_{(Cylinder)} =\: 2 \times \dfrac{22}{7} \times 7 \times 20$

$\implies \sf C.S.A_{(Cylinder)} =\: \dfrac{44}{7} \times 140$

$\implies \sf C.S.A_{(Cylinder)} =\: \dfrac{6160}{7}$

$\implies \sf\bold{\red{C.S.A_{(Cylinder)} =\: 880\: cm^2}}$

$\therefore$ The curved surface area of a cylinder is 880 cm² .

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☆ Total Surface Area or TSA Of Cylinder :

Given :

• Radius = 7 cm
• Height = 20 cm

According to the question by using the formula we get,

$\bigstar \: \: \sf\boxed{\bold{\pink{T.S.A_{(Cylinder)} =\: 2{\pi}r(r + h)}}}\: \: \: \bigstar$

where,

• T.S.A = Total Surface Area
• π = Pie or 22/7
• r = Radius
• h = Height

By putting the values we get,

$\implies \sf T.S.A_{(Cylinder)} =\: 2 \times \dfrac{22}{7} \times 7(7 + 20)$

$\implies \sf T.S.A_{(Cylinder)} =\: \dfrac{44}{7} \times 7(27)$

$\implies \sf T.S.A_{(Cylinder)} =\: \dfrac{44}{7} \times 189$

$\implies \sf T.S.A_{(Cylinder)} =\: \dfrac{8316}{7}$

$\implies \sf\bold{\red{T.S.A_{(Cylinder)} =\: 1188\: cm^2}}$

$\therefore$ The total surface area of a cylinder is 1188 cm² .

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Answer 2

Question :-

• The Radius of a Right Circular Cylinder is 7 cm and it's height is 20 cm . Find its Curved Surface Area and Total Surface Area .

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Answer :-

• Curved Surface Area = 880 cm² .
• Total Surface Area = 1188 cm² .

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Explanation :-

• Here, Radius of Cylinder is given 7 cm and Height of Cylinder is 20 cm . And, we have to calculate the Curved Surface Area and the Total Surface Area .

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◆ First , we will find Curved Surface Area :-

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$\dag \: \sf{Curved \: Surface \: Area = 2\pi r h} \\ \\ \dashrightarrow \: \sf{C.S.A = 2 \times \frac{22}{7} \times 7 \times 20 } \\ \\ \dashrightarrow \: \sf{C.S.A = \frac{44}{7 } \times 7 \times 20 } \\ \\ \dashrightarrow \: \sf{C.S.A = \frac{44}{7} \times 140 } \\ \\ \dashrightarrow \: \sf{C.S.A = \frac{6160}{7} } \\ \\ \dashrightarrow \: \sf{C.S.A = 880 \: cm {}^{2} }$

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◆ Now , we will find Total Surface Area :-

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$\dag \: \sf{Total \: Surface \: Area = 2 \pi r \: \: (R + H)} \\ \\ \dashrightarrow \: \sf{T.S.A = 2 \times \frac{22}{7} \times 7 \: \: (7 + 20)} \\ \\ \dashrightarrow \: \sf{T.S.A = \frac{44}{7} \times 7 \: \: (7 + 20) } \\ \\ \dashrightarrow \: \sf{T.S.A = \frac{44}{7} \times 7 \: \: (27)} \\ \\ \dashrightarrow \: \sf{T.S.A = \frac{44}{7} \times 189 } \\ \\ \dashrightarrow \: \sf{T.S.A = \frac{8316}{7} } \\ \\ \dashrightarrow \: \sf{T.S.A =1188 \: cm {}^{2} }$

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Hence :-

• Curved Surface Area = 880 cm² .
• Total Surface Area = 1188 cm² .

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