Question

Find the curved surface area and volume of cylinder whose hieght is 21cm and area of its one end is 154cmsq

Answer 1

Answer:

r = ?

height = 21cm

Area of it's one of it's end

$= \pi \: {r}^{2}$

$154 = \frac{22}{7} {r}^{2}$

$1078 = {r}^{2} 22$

${r}^{2} = \frac{1078}{22}$

${r}^{2} = 49$

r = 7cm

CSA of cylinder = 2πrh

$= 2 \times \frac{22}{7} \times 7 \times 21$

cancelling 7 we get,

$= 2 \times 22 \times 21$

CSA = 924 cm ^2

Volume of cylinder

$= \pi \: {r}^{2} h$

$= \frac{22}{7} \times 7 \times 7 \times 21$

cancelling 7 we get,

= 22x7x21

Volume = 3234

Answer 2

Answer:

921 cm^2

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Given:

Area of one of the circle = 154cm^2.

Height of the cylinder = 21cm

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To find:

CSA of cylinder

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Solution:

Area of circle= πr^2

154= πr^2

154= (22r^2)/7

154×7 = 22r^2

1078/22 = r^2

49 = r^2

r=√49

r=7

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CSA of cylinder = 2πrh

= (2×22×7×21)/7

=6468/7

=924 cm^2

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Volume of cylinder = πr^2h

= (22×7×7×21)/7

= 3234 cm^3

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Hope it helps.

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