1. CIRCLES

2. CIRCLES
A circle is a shape with all points the same distance from its center.
A circle is named by its center.
Thus, the circle to the right is called circle A since its center is at point A.
Some real world examples of a circle are a wheel, a dinner plate and (the surface of) a coin.
ALL CIRCLES ARE 360 DEGREES

3. DIAMETER OF A CIRCLE
The distance across a circle through the center is called the diameter. A real-world example of diameter is a 9-inch plate.

4. RADIUS OF A CIRCLE
The radius of a circle is the distance from the center of a circle to any point on the circle.
If you place two radii end-to-end in a circle, you would have the same length as one diameter.
Thus, the diameter of a circle is twice as long as the radius. 

5. CHORD A chord is a line segment that joins two points on a curve.
In geometry, a chord is often used to describe a line segment joining two endpoints that lie on a circle.
The circle to the right contains chord AB

6. EVERY DIAMETER IS A CHORD BUT NOT EVERY CHORD IS A DIAMETER
A DIAMETER MUST PASS THROUGH THE CENTER OF THE CIRCLE

7. and the points ON the circle
A circle divides the plane into three parts:the points INSIDE the circle the points OUTSIDE the circle
and the points ON the circle
the points inside the circle the points outside the circle the points on the circle

8. CIRCUMFERENCE OF A CIRCLE
The circumference of a circle is the distance around the circle
The circumference of a circle can be found by multiplying pi ( π = 3.14 ) by the diameter of the circle.

9. If a circle has a diameter of 4, its circumference is 3. 14. 4=12
If a circle has a diameter of 4, its circumference is 3.14*4=12.56 If you know the radius, the diameter is twice as large.

10. AREA OF A CIRCLE
The area of a circle is the number of square units inside that circle.
A = π × r2

11. Angles of a Circle
A full circle measures 360 degrees The formulas for the angles of a circle is 2x pi

12. SECTOR OF A CIRCLE Slices There are two main "slices" of a circle:
The "pizza" slice is called a Sector.
And the slice made by a chord is called a Segment.

13. Write the formula for the circumference and the area of a circle
Home work:
Draw a circle and name the parts on graph paper- use your protractor to draw the circle. 10 pts.
Show in a picture:
Area
Circumference
Center
Sector
Radius
Diameter
Chord
Write the formula for the circumference and the area of a circle
We will work on the area and circumference of a circle in class tomorrow.