Area of a circleArea of a circle
TThe AREA of a circle?he AREA of a circle?2r
2rr
To find the area of a circle, first consider a square…
The area of this square
in terms of r (radius) is…
A= 2r x 2r = 4r2
What about the AREA of a What about the AREA of a circle?circle?2r
2r
Now think about a circle inside the square…
The area of the circle must be less than the area of the square…
A < 4r2
r
Area = ? xr2
Finding a formula for the area of a circle
C = πd or C=2πrSemi - circle=πr
Area of Rectangle= Base x Height
Area = πr x r
Area =πr2
Summary: How to Calculate the Area of the circle
1= Figure out the length of the radius. This
may be as simple as dividing the diameter by 2.
2= Note the formula. The formula for finding
the area of a circle is:
Here I present a short instruction of the practical use of the “Pie" formula. The instructions I wrote here are based on a short problem from our Math’s Workbook.
3= Multiply the radius by itself to square it. 4= Multiply by pie.
>> If the instructions say "leave in terms of pie”, then just stick the pie onto your number.
>> If the instructions say anything about rounding, replace pi with 3.14 or use your calculator's pi button.
Here is an example:
Summary: How to Calculate the Area of the circle
•Occasionally you will see a circle inside of a square. The side length of the square matches the diameter of the circle.
•Occasionally you may see a square inside of a circle. The diagonal of the square is also the diameter of the circle.
Summary: How to Calculate the Area of the circle
The Summary of The Area of a The Summary of The Area of a CircleCircle
A circle is defined by its diameter or radius
Diameter
Rad
ius The perimeter or circumference of a circle
is the distance around the outside
The area of a circle is the space inside it
The ratio of π (pi)diameter
ncecircumfere
ππ is an irrational number whose value to 15 decimal places is an irrational number whose value to 15 decimal places isis
ππ = 3.14159265358979.... We usually say = 3.14159265358979.... We usually say ππ ≈≈3.143.14 The area is found
using the formula
A=πr2
By Filip Car 8MP.S. If you have any feedback, feel free to contact me by [email protected] or just give it to me in class
Recommended
