Lesson 8.2
Objective: To find the circumference
and areaof circles.
 Parts of a Circle
 Circumference / Perimeter
 Area
Find the area of the trapezoid
a)
b)
A= 31.8 cm²
A= 12.6 ft²
https://www.youtube.com/watch?v=cC0fZ_lkFpQ
 Closed plane figure formed by a set of points that are
all the same distance (equidistant) from a centre point.
Circle P
P
 Is a line segment that has its endpoints on
the circle.
B
A
Chord: AB
P
 Line segment with one endpoint at the
center of a circle and the other endpoint
on the circle.
P
Radius: PK
K
 Is a chord that passes through the centre.
C
 Diameter: CD
P
D
 Straight line that touches the circle at a
single point.
X
Y
Tangent: XY
 Is a tool used to construct circles.
 There is a proportional relationship between
the diameter and circumference of any circle.
 The constant of proportionality is pi π.
 Is the distance AROUND the circle
 It is a form of perimeter
C ≈ 158.57 meters
d ≈ 18 inches
r ≈ 1.26 centimeters
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