Question

Find the radius of a cylinder whose csa isc 2/3 times the sum of the areas of the 2 circular surfaces.The height of the cylinder is 15 cm

Answer 1

Given , height of cylinder h = 15 cm

since , we know that areas of two circular surfaces of cylinder are πr^2 , πr^2 .

Find the sum of areas :
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sum of areas = πr^2 + πr^2 = 2πr^2

CSA of cylinder = 2πrh

according to the given statement :
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CSA of cylinder = (2 / 3 ) × sum of the areas of two circular surfaces .

2πrh = (2 / 3 ) × 2πr^2

2h = (4 / 3 ) ×πr^2 / πr

2h = 4r / 3

6h = 4r


6 × 15 = 4r

4r = 90

r = 22.5 cm

therefore, radius of cylinder = 22.5 cm

Answer : radius = 22.5 cm

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