Curved surface area of a cylinder having base radius “r” and height “h” is equal to __________(a) 2πrh + 2πr^2(b) 2πr^2(c) 2πrh(d) 4πr^2The question was asked during an interview for a job.My question is from Surface Area of a Right Circular Cylinder topic in chapter Surface Areas and Volumes of Mathematics – Class 9

Curved surface area of a cylinder having base radius “r” and heigh

1.	Curved surface area of a cylinder having base radius “r” and height “h” is equal to __________(a) 2πrh + 2πr^2(b) 2πr^2(c) 2πrh(d) 4πr^2The question was asked during an interview for a job.My question is from Surface Area of a Right Circular Cylinder topic in chapter Surface Areas and Volumes of Mathematics – Class 9
Answer» Correct answer is (c) 2πrh For explanation: If we unfold the cylinder GIVEN in the above figure, the area of the rectangle gives us the area of CURVED surface area of a cylinder (As shown in the figure below). One side of the rectangle is EQUAL to “h” and the other side is equal to perimeter of circular edge of the cylinder, i.e. “2πr”. HENCE, the curved surface area of the cylinder = 2πr * h = 2πrh.

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