The document discusses how to calculate the area of a circle. It explains that the area of a circle is equal to π multiplied by the radius squared (A=πr2). It provides examples of using a square to visualize the relationship between the radius and area, and derives the area formula by relating a circle to a rectangle. The key steps are to determine the radius, note that the area formula for a circle is A=πr2, and plug the radius measurement into the formula to calculate the area.

2. The AREA of a circle?
2r
2r
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
r

3. What about the AREA of a 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

4. Now Finding a formula
for the
Area of a circle

5. C = πd or C=2πr
Semi - circle=πr

6. Area of Rectangle= Base x Height
Area = πr x r
Area =πr2

7. 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:

10. •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

11. The Summary of The Area of a Circle
A circle is defined by its diameter or radius
Diameter
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
nce
circumfere
π is an irrational number whose value to 15 decimal places is
π = 3.14159265358979.... We usually say π ≈3.14
The area is found
using the formula
A=πr2