Vocab & Concepts
400 POINT BONUS!! What is the name of a line or line segment that goes from the edge of a circle to the center?
A Radius
Order these expressions from least to greatest:
4pi, 12.5, 6, 4+2pi
6, 4+2pi, 12.5, 4pi
What is the name of a line or line segment that goes from one edge of a circle to another edge that passes through the center?
A diameter
Draw a picture of a circle with the radius labeled.
Check answers on whiteboard
Mary had a new circular pool installed in her backyard. If she swims from the edge of the pool to the middle, she swims 12.5 feet. What is the diameter of the pool?
25 feet
DAILY DOUBLE!! Joshua has a round table with a diameter of 5 feet. What is the distance around the outside of the table?
15.7 feet
If you take the distance around the outside of any size circle and divide by the diameter, what number will you always get?
Pi (3.141592653...)
DAILY DOUBLE!!! Does a radius and circumference have a proportional relationship?
Yes, recall the graph of this on the mid topic quiz, the constant of proportionality was 2 pi or about 6.28
The diameter of the circle at half-court in Wheeler's gym is 12 feet. What is the area of that circle?
113.04 square feet
Mrs. Costello has a plate with a diameter of 12 inches. What is the circumference of that plate?
37.68 inches
From what language do we get the term 'pi'?
Greek
Give a real life example of when you would need to calculate the perimeter of a circle.
Answers vary.
Example: Calculating the distance Mrs. V goes on her bike if the tire makes 10 rotations.
DAILY DOUBLE!! Aliens landed in Roswell and created a circle in the ground that has a circumference of 56 meters. What would the radius of that circle be?
Approximately 8.9 meters
Mrs. Van Horn's dog has a water bowl that has a circumference of 31.40 inches. What is the diameter of the bowl?
10 inches
Anthony bought a large 18 inch pizza at Mystic Pizza. What is the distance around the outside of the pizza?
56.52 inches
The diameter of a bike tire is 10 pi inches, about how many full rotations will the wheel make to go 100 feet?
About 38 full rotations.
What part of a circle is related to one full rotation?
the circumference
The distance around a bicycle tire is 78.5 inches. How long is one of the spokes?
12.5 inches
Mrs. Charles has a clock with a minute had that goes from the middle of the clock to the edge. The minute hand is 16cm long. What is the diameter of the clock?
32 cm
Chase bought new tires for his 4 wheeler. The radius of the tire is 18 inches. What is the circumference of four tires added together?
about 452.16 inches
DAILY DOUBLE!! Give an real life example of when you would need to calculate the area of a circle.
Check student answers.