Post on 23-Dec-2015
Objectives/Assignment
• Find the circumference of a circle• Use circumference to solve other
problems
Definitions
• Circle – is the set of all points in a plane that are equidistance from a given point on that plane
• Center- “The given“ point on the plane• Radius- A segment that has one endpoint
at the center of a circle and the other end point on the circle itself
Definitions• Chord – A segment that has both
endpoint on a circle• Diameter - Is a chord that contains
the center of the circle.• Circumference - The distance around
the circle
Finding circumference
• The circumference of a circle is the distance around the circle.
• For all circles, the ratio of the circumference to the diameter is the same.
• This ratio is known as or pi.
Circumference of a Circle
• The circumference C of a circle is C = d or C = 2r, where d is the diameter of the circle and r is the radius of the circle.
diameter d
Example # 2
Find • a. the circumference of a circle with
radius 6 centimeters • b. the radius of a circle with
circumference 31 meters.
Solution:C = 2r = 2 • • 6 = 12 37.70
So, the circumference is about 37.70 cm.
C = 2r31 = 2r31 = r
4.93 rSo, the radius is
about 4.93 cm.
2
a.
b.
Take Notes
C = 2 * 3.14 * 14 C = 43.9
D² = 10² + 24² D² = 100+ 576D = 26C = 26* 3.14 = 81.7
D² = 5² + 5² D² = 25 +25D = 7.1C = 7.1* 3.14 = 22.2
4x + 35 = 9x +530 = 5xX = 6
AE = = 4 * 6 + 35 = 59
ED = = 9 * 6 + 5 = 59
62 =59- 59- 180 , 180 = 3ے + 2ے + 1ے
4ے = 3ے ( vertical) = 62
121 =62 + 59 = 3ے + 1ے
121 = 62+ 59 = 2ے + 4ے