Lori Bonn

Word SplashWrite down any word that you can think of to describe the word

below

Circle radius

sphere

clock

flat ball

diameter

circumference

coins

sun

ring center

Write down two words you would like to learn more about today?

Characters: Lady Di, her son radius, and his father Sir Cumference

They had to yell down the table, so the king needed a solution. Sir Cumference’s solution was a square, but the knights at the corners whispered.

As a rhombus, the knights at the corners were jabbed in the stomach.

The octagon table did not have enough sides for the twelve knights.

The oval was too narrow and the knights bumped into each other.

As the family rode in the woods they found another possible solution.

The Parts of a Circle

circumference is the measurement around the outside of the circle

center point

radius is the distance from the center point to the outside of the circle

Diameter is the distance from one side of the circle to the other side going through the center point

Circle Radius Diameter

Circumference

A

B

C

D

E

F

G

H

I

J

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What is the relationship between the radius and diameter?

The diameter is twice the radius, OR the radius is half the diameter

R x 2= D

D ÷ 2 = R

What is the relationship between the diameter and the circumference?

The circumference is approximately 3 times the diameter

D x 3= C

Will this pattern stay the same with bigger circles?

What is the approximately 3?

The piece that is not covered is .14 of the missing diameter. This is called ∏ = 3.14

Compare and contrast the measuring of a perimeter and a

circumference. perimeter circumference

Area

You can use tiling to find the area of a circle, but will you always have tiles? What do you do with the partial tiles?

Cut apart the 8 segments of the circle to form a parallelagram

What is wrong with this parallelogram?

segments

Cut apart the 24 segments of the circle and rearrange them to form a parallelogram

Length x height = areaRearrange sections of circle to form parallelogram.

The top and bottom would be the circumference (d X 3.14) so, just the bottom would be half the diameter (radius)

R X 3.14

Radius

Area = r ² X 3.14