# Circle Area Formula along with Example Problems

After we previously discussed the formula around a circle, this time we will discuss material about the formula for the area of ​​a circle, we will describe in detail and in full the understanding of a circle, understanding the area of ​​a circle, formulas, and examples of problems from the area of ​​a circle.

## Definition of Circles

What is a circle? You already know, a circle is a two-dimensional image as a set of all points that have the same distance from the midpoint in a plane.

The circle also has three main and important points, namely the midpoint called the center of the circle, the center of the circle leading to the outer point called the radius of the circle, the outer point of the circle passing through the center until the outer point is called the diameter of the circle. The following are examples of images that mentioned the main points.

Information :

• p = center of circle
• d = circle diameter

## Definition of Area of ​​a Circle:

What is the area of ​​a circle? you already know, the area of ​​a circle is an area within a circle that is also bounded by the circumference of a circle.

## Circle Area Formula:

#### π xr 2 or  πr2 = ¼ π d 2

above is the circle area formula, it can be concluded that if you want to find the area of ​​a circle with radius r and ∏ = 22/7 or 3.14 that can be used.

## Examples of Circle Area Problems

Example Problem 1

1 . A motorcycle wheel is known to have a diameter of 42 cm. Look for the wide circle of the motorcycle’s wheels!

Settlement:

Note: d = 42 cm

Answer: because d = 2 times r then that:

r = d / 2

r = 42/2

r = 21 cm

L = π xr 2

L = 22/7 x 21 2 = 1,386 cm 2

So, the area is = 1,386 cm 2

Example Problem 2

2.  There is a car that has a radius of 20 cm, find and calculate the area of ​​the circle!

Settlement:

Note: r = 20 cm

L = π xr 2

L = 3.14 x 20 2 = 1,256 cm 2

So, the area is = 1,256 cm 2

Example Problem 3

3.  There is a circle that has a diameter of 60 cm. Search and calculate the area of ​​the circle!

Settlement:

Note: d = 60 cm

Answer: because d = 2 times r then that:

r = d / 2

r = 60/2

r = 30 cm