The formula for the area of a circle with an example problem
Formula.co.id – After previously we discussed about circle circumference formula this time we will discuss material about the formula for the area of a circle, we will describe it in detail and complete from the meaning of a circle, understanding the area of a circle, formulas, and examples of problems from area circle.
Table of contents :
Definition of Circle
What is a circle? you already know, Circle is a two-dimensional image and as a set of all points that have a distance from the same center point in a plane.
The circle also has three main and important points, namely the midpoint is calledcircle center, the center of the circle to the outermost point is called circle radius, the outermost point of the circle passing through the center to the outermost point is called circle diameter. The following is an example of an image that mentions the main point.
Information :
- p = center of circle
- r = radius of circle
- d = diameter of circle
Definition of area of a circle:
What is the area of a circle? you already know, Circle Area is the area inside a circle bounded by the circumference of the circle.
The formula for the area of a circle:
x r2 or r2 = d2
above is the formula for the area of a circle, it can be concluded that if you want to find the area of a circle with radius r and = 22/7 or 3.14 you can use it.
Example Problem Area of a Circle
Example Question 1
1. A motorcycle wheel is known to have a diameter of 42 cm. Find the area of the circle of the motorcycle wheel!
Solution:
Is known: d = 42 cm
Asked: L = ….?
Answer: because d = 2 times r then it is:
r = d/2
r= 42/2
r = 21 cm
area =
L = x r2
L = 22/7 x 212 = 1.386cm2
So, area is = 1.386cm2
Example Question 2
2. There is a car that has a radius of 20 cm, find and calculate the area of the circle!
Solution:
Is known: r = 20 cm
Asked: L=….?
Answer:
L = x r2
L = 3.14 x 202 = 1.256cm2
So, area is = 1.256cm2
Example Question 3
3. There is a circle that has a diameter of 60 cm. Find and calculate the area of the circle!
Solution:
Is known: d = 60 cm
Asked: L = ….?
Answer: because d = 2 times r then it is:
r = d/2
r= 60/2
r = 30 cm
area =
L = x r2
L = 3.14 x 302 = 2.826 cm2
So, area is = 2.826 cm2
Example Question 4
4. There is a circular field that has a radius of 77 cm. Find and calculate the area of the circle!
Solution:
Is known: r = 77 cm
Asked: L=….?
Answer:
L = x r2
L = 22/7 x 772 = 18,634 cm2
So, area is = 18,634 cm2
Example Question 5
5. There is a circular field that has a radius of 33 cm. Find and calculate the area of the circle!
Solution:
Is known: r = 33 cm
Asked: L=….?
Answer:
L = x r2
L = 3.14 x 332 = 3,419.46cm2
So, area is = 3,419.46 cm2
Example Question 6
6. There is a circular field that has a radius of 56 cm. Find and calculate the area of the circle!
Solution:
Is known: r = 56 cm
Asked: L=….?
Answer:
L = x r2
L = 22/7 x 562 = 9.856cm2
So, area is = 9.856 cm2
Example Question 7
7. A motorcycle wheel is known to have a diameter of 98 cm. Find the area of the circle of the motorcycle wheel!
Solution:
Is known: d = 98 cm
Asked: L = ….?
Answer: because d = 2 times r then it is:
r = d/2
r= 98/2
r = 49 cm
area =
L = x r2
L = 22/7 x 492 = 7,546 cm2
So, area is = 7.546cm2
Example Question 8
8. A motorcycle wheel is known to have a diameter of 38 cm. Find the area of the circle of the motorcycle wheel!
Solution:
Is known: d = 38 cm
Asked: L = ….?
Answer: because d = 2 times r then it is:
r = d/2
r= 38/2
r = 19 cm
area =
L = x r2
L =3.14 x 192 = 1,133.54cm2
So, area is = 1,133.54 cm2
This is a complete discussion about how to calculate the formula for the area of a circle along with examples of questions and their discussion, hopefully it will be useful...