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Area & Perimeter Area: Covering Perimeter: Surrounding Polygons: Triangles, Rectangles, Squares, Parallelograms, Trapezoids
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CirclesCircumference, Diameter and Radius
Important Info.You’ll need: notebook, pencil, and formula card.Pause. Rewind. Volume.Questions?
Area & PerimeterArea: CoveringPerimeter: SurroundingPolygons: Triangles, Rectangles, Squares, Parallelograms, Trapezoids
What is a circle?Not a polygon.
A plane figure with three or more straight sides and angles.
Definition: a closed plane figure made up of all the points the same distance from a point called the center.
E
Circle E
F
G
H
EF EGEH
==
radius
E
Circle E
F
EF
diameter
I+ EI= IF
½½
radius + radius = diameterr + r = d2r = d
Things You Should Know...
Radius (Plural: Radii)
A straight line from the center of a circle to it circumference.
It is half of the diameter.
Radius = r
Diameter
A straight line passing through the center of a circle connecting 2 points on the circumference.
It is twice the radius.
Diameter = d
CircumferenceDistance around a circle.C=2πr orC=πdπ = 22/7 ≈ 3.14
Finding CircumferenceC=2πr
Use this formula when you are given the radius.
C=πd
Use this formula when you are given the diameter.
Find the circumference of each circle. Use 3.14 for π.
4 cm
Find the circumference of each circle. Use 3.14 for π.
6 in
Find the circumference of each circle. Use 3.14 for π.
2.1 m
Find the circumference of each circle. Use 3.14 for π.
3.3 ft
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Before school tomorrow.Extra help on Mondays and Wednesdays.
