Bellwork What strategy should be used to find a

fraction between 7/8 and 9/10?

Daily Activities

TIMED SKILL DRILLS HOMEWORK REVIEW

CircumferenceMS Framework Ob j: 4ac

8th Grade Pre-Algebra

By: Mrs. Davis

What is circumference and how is it used in the real world?

Definition: The distance AROUND the outside edge of the CIRCLE.

Relate:Perimeter

Confident Teen Volunteer Needed!

Math in the Real WorldWalking Trail – Reading Problem

Mrs. Davis is trying to tone up! Each morning she “speed walks” one time around circular walking trail. The trail has a diameter of 50 yards. What is the distance 1 time around the trail?

Math in the Real WorldFerris Wheel – Reading Problem

The DCMS math teachers took a ride on a Ferris Wheel. The radius of the Ferris Wheel is 38 m. What distance would they travel in one revolution?

Who was the biggestCHICKEN???#Coach Stiles

Math in the Real WorldHorse Lunging Arena – Reading Problem

Lunging is a method used to exercise a horse or to teach him something new without a rider on his back.

A rope is attached to the horse’s harness. The rider then stands in the center of a ring and directs the horse to move in a circular rotation.

A jumping horse lunging around an arena 60 feet in diameter travels what distance in 1 rotation?

Radius:Is the distance from the center of the circle to the outer edge.

3 in

Words you need to know when dealing with circles.

Diameter:Is the distance from one side of the circle to the other.

Circles

14 m

Pi ( ):The number used when working with circles.

3.14

Finding the Circumference of a Circle.

• Circumference is the distance around the outer edge of a circle.

• To find the circumference of a circle use the formula:C = ________

14 m3 inDiameter (d)

Radius (r)

C = ____ x ____ x ____

C = ______________

radius = ______

C = ____ x ____ x ____

C = ______________

Guided Practice

Mr. Jones is planning on building a circular shaped swimming pool in his backyard. If the radius of the pool is 15 ft, what is the distance around the outer edge of the pool?

C = 2 r

C = ____ x ____ x ____

C = ______________

Circumference Key Words

· Outer Edge· Around· Rotation· Revolution

You Try

Mrs. Davis is trying to tone up! Each morning she “speed walks” one time around a circular walking trail. The trail has a diameter of 50 yards.

What is the distance 1 time around the trail?

C = 2 r

C = ____ x ____ x ____

C = ______________

Circumference Key Words

· Outer Edge· Around· Rotation· Revolution

You Try

Mark and Amanda took a ride on a Ferris Wheel. The radius of the Ferris Wheel is 38 m. What distance would you travel in one revolution?

C = 2 r

C = ____ x ____ x ____

C = ______________

You Try

A jumping horse lunging around an arena 60 feet in diameter travels what distance in 1 rotation?

What key words tell you that we are dealing with circumference?

C = ____ x ____ x ____

C = ______________

C = 2 r

Double-Bubble Map

Distance around the outer edge of a shape.

Perimeter

Circumference

Pertains to polygons.

Pertains to circles.

Calculate by adding the sides together.

9 m

9 m

6.5 m

Perimeter Vs. Circumference

6.5 m

Calculate using formulas.

C = _________

What is the diameter of a circle? What is the radius?What is the formula for finding circumference?What number do we use for ?How do you find the radius if only the diameter is given?9 cm

ClosureWhat is the BIG CONNECTION between

perimeter and circumference?