Question

A cylinder is made by joining the breadth sides of rectangular sheet of length l cm breadth b cm. Then TSA of cylinder is

Answer 1

T.S.A of cylinder = C.S.A + 2 Area of bases

= 2πrh + 2πr^2

= 2πr ( h + r )

Answer 2

Given :

A cylinder is made by joining breadth sides of a rectangle

The length of rectangle = l cm

The breadth of rectangle = b cm

To Find :

Total surface Area of Cylinder

Solution :

when we join two ends of a rectangle across its breadth a cylinder formed

So Length of cylinder = breadth of rectangle

  Length of cylinder = b cm

  Length of rectangle = circumference of circular base

Or,                         l = 2 π r

∴ radius of cylinder = r = l/2π

So, Total surface area = curved surface area + 2 × base area

T S A = 2 π r h + 2 × π r²

T S A = 2 π r b + 2 × π(l/2π)²

Hence, The Total surface Area of the cylinder is 2 π r b + 2 × π(l/2π)²