Formulas
Definitions
Circumference of Circles
Area of Circles
100
How do we find the radius?
r=d/2
100
What is the radius of a circle?
The radius is the distancefrom the center to anypoint on the circle.
100
circle with radius of 3cm
18.8
100
circle with diameter of 7m
38.5m
200
How do we find the diameter of a circle?
d=2r
200
What is the diameter of a circle?
The diameter is thedistance across the circlethrough the center.
200
circle with diameter of 3ft
9.4 ft
200
circle with radius of 10cm
314.2 cm
300
How do we find the circumference of a circle?
or C = πd
300
What is the circumference of a circle?
The distance around a circle is called the circumference.
300
circle with radius of 7.3cm
45.9cm
300
circle with radius of 11in
380.13in
400
How do we find the area of a circle?
400
What is a circle?
A circle is the set of all points in a plane that are the same distance from a point called the center.
400
circle with diameter of 9.9cm
31.1 cm
400
circle with diameter of 11cm
95.03cm
500
How do we find the area of a semicirlce?
A = (π * r^2) / 2
500
What is a composite figure?
A composite figure is made up of triangles, squares, rectangles, semicircles, and other two-dimensional figures.
500
circle with diameter of 20.6yd
64.7 yd
500
circle with radius of 14mm
615.8mm