Parts of Circle
A segment from the center of the circle to the outside.
radius
Name the circle.
Circle O
If the central angle is 45 degrees, what is the measure of the arc?
45 degrees
Formula to find circumference.
C=pi*d, C=2*pi*r
Formula to find area of circle.
A=pi*r^2
A segment with endpoints on the outside of the circle, that goes THROUGH the center.
Diameter
Name a radius.
Segments OC, OB, OA
Explain the relationship between a radius and a diameter.
The diameter is twice the radius. Or, the radius is half the diameter.
The diameter of a circle is 16, what is the circumference? (Leave your answer in terms of pi)
C=16*pi
Find the area of a circle that has a radius of 6. (Leave your answer in terms of pi)
A=36pi
A segment whose endpoints are on the outside of the circle.
Chord
Name a diameter.
Segment AB
In the equation of a circle (x-h)^2 + (y-k)^2 = r^2, what does the (h, k) represent?
The center of the circle.
The radius of circle is 1. What is the circumference? (Leave your answer in terms of pi)
C=2*pi
Find the area of circle that has a diameter of 10. (Round your answer to nearest TENTH)
A=78.5
A line that intersects the circle at ONE point.
Tangent
Name a chord.
Segment DE
How do you know if a line is TANGENT to a circle?
It creates a right angle with the radius.
C=25.1
The area of a circle is 154. What is the radius?
r=7
A line that intersects the circle at 2 points.
Secant
Name a secant.
Line DE
Where does the value of pi come from?
The ratio of a circle's circumference to its' diameter.
The circumference of a circle is 37.7. What is the radius?
r=6
Find area of a 90 degree sector of a circle that has a radius of 4. (Round your answer to the nearest TENTH)
A=12.6