The T.S.A. of a cylinder is 462 cm^2. If C.S.A. is one-third of its T.S.A. .Find the volume of the cylinder.
Answers
Solution :
TSA of the cylinder = 462 cm²
Given :
CSA of the cylinder = 1/3rd of its TSA
= ( 1 / 3 ) × 462 = 154 cm²
We know that
TSA of a cylinder = CSA of the cylinder + 2 × ( Area of base i.e circle )
Let the Area of the base i.e circle be x cm²
⇒ 462 = 154 + 2x
⇒ 462 - 154 = 2x
⇒ 308 = 2x
⇒ x = 308 / 2
⇒ x = 154
⇒ Area of base circle = 154 cm²
Let the base radius of the cylinder be ' r ' cm
⇒ πr² = 154 cm² --- EQ( 1 )
⇒ 22/7 × r² = 154
⇒ r² = 154 × 7 / 22
⇒ r² = 7²
⇒ r = 7
i.e Base radius of the cylinder ( r ) = 7 cm
Let the height of the cylinder be ' h ' m
CSA of the cylinder = 2πrh sq.units
⇒ 154 = 2 × 22/7 × 7 × h
⇒ 154 = 44h
⇒ h = 154 / 44
⇒ h = 7 / 2
i.e Height of the cylinder ( h ) = 7 / 2 cm
Volume of the cylinder = πr²h cu.units
From EQ( 1 )
= 154 × 7 / 2
= 539 cm³
Therefore the volume of the cylinder is 539 cm³.
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