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
a)lb + 2(l+b ) cm square units
b)lb cm square units
c)2πlb cm square units
d)2πl(l+b)cm square units​

Answer 1

Answer:

d

Step-by-step explanation:

d) 2πl(l+B)cm square units

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 = $\dfrac{l}{2\pi }$

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 ($\dfrac{l}{2\pi }$) ²

Hence, The Total surface Area of the cylinder is  2 π r b + 2 × π ($\dfrac{l}{2\pi }$) ²  Answer