Question

What is Surface area of cylinder ?

Answer 1

The surface area of a cylinder can be found by breaking it down into three parts:
1. The two circles that make up the ends of the cylinder.
2. The side of the cylinder, which when cut and "unrolled" is a rectangle.

We can observe that the cylinder is made up of two circular disks and a rectangle.

1. The area of each end disk can be found from the radius r of the circle.
The area of a circle is $\pi \left(r^2\right)$, so the combined area of the two disks is twice that, or $2\pi \left(r^2\right)$.
2. The area of the rectangle is the width times height.
The width is the height h of the cylinder, and the length is the distance around the end circles. This is the circumference of the circle and is
$2\pi r$. Thus the rectangle's area is $2\pi r\times h$.Combining these parts we get the final formula:
where:
$\pi$ is Pi, approximately 3.142
r is the radius of the cylinder
h height of the cylinder