###### GRADE-9 NCERT CHAPTERS

- QUADRILATERALS

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# Tag: Surface area of the cylinder

## Grade-9 NCERT

###### GRADE-9 NCERT CHAPTERS

## How can find the surface area of the cylinder

- QUADRILATERALS

How can find surface area of cylinder

**Surface area of the cylinder =2πr(H+r)**

Dear friends,

In this post I will explain how we can find out the surface area of the cylinder.

Consider cylinder having height H and the diameter of the base circle D as shown in the figure FIG1-A. Now consider a rectangular paper having the height “H” as same as the height of the cylinder height “H”. Also assume that the length of the paper “L” is just enough to cover the complete the curved surface area of the cylinder as shown in the FIG1-B.

So now we know the area of the paper is H*L.

We can also know that the length of the paper is equal to the circumference of the base circle of the cylinder.

So circumference of the circle is = 2πr

so area of the paper = H*2πr.

There for the

Total curved surface area of the cylinder =H*2πr.

Now we have to consider the area of the base and top circle, inorder to get the total surface area of the cylinder.

we know that the area of the circle = πr².

area of 2 circle =2πr².

So the total surface area of the cylinder = H*2πr +2πr² = 2πr(H+r)

There for

**Surface area of the cylinder =2πr(H+r)**

Where H is the height of the cylinder and “r’ is the radius of the cylinder.

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