Unit 3, Lesson 4
Applying Circumference
Grade 7
4.1
Warm-up
For each picture, which measurement is shown? Be prepared to explain your reasoning.
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Wagon wheel: 3 feet
A picture of a wagon wheel with a measuring tool starting from one point on the wheel, goes through the wheel center to a point on the other side of the wheel. -
Plane propeller: 24 inches
A picture of a plane propeller with three identical propeller blades. A measuring tool starts from the center of the propeller and goes to the end of the blade. -
Sliced orange: 20 centimeters
A picture of a sliced orange. A measuring tool goes around the entire circular region of the orange.
4.4
Activity
The field inside a running track is made up of a rectangle that is 84.39 m long and 73 m wide, together with a half-circle at each end.
A picture of a field inside a running track. The field inside the track is composed of a rectangle, indicated by two dashed vertical lines labeled 73 meters and a horizontal length labeled 84 point 3 9 meters. There is a semi circle on each vertical side of the rectangle. The running track goes completely around the field and has a width of 9 point 7 6 meters.
- What is the distance around the inside of the track? Explain or show your reasoning.
- The track is 9.76 m wide all the way around. What is the distance around the outside of the track? Explain or show your reasoning.
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