Circle information
Circumference
Area
Circle graphs
Others
100
What would you use from your protractor kit to make a circle?
Compass
100
What does circumference mean?
the distance around a circle (like perimeter of square)
100
What is the equation for the area of a circle?
A=pir^2
100
How much should all the percents in a circle graph add up to?
100%
100
What is the area of a circle with a 2.4 cm radius? (to the nearest tenth)
A=pi(2.4)^2=18.1cm^2
200
What is (distance around) divided by (diameter)?
C/d=pi
200
What is the equation for circumference? (both equations)
c=pid or c=2pir
200
If you have a circular mirror with a radius of 20cm, what is its area?
A=pi(20)^2= 400π cm^2
200
If a class has 28 students and 40% of them have blonde hair, how many students have blonde hair (round to the nearest whole number?
40%=0.40
28*0.40=11.2
11 or 12 students have blonde hair
200
TRUE or FALSE: If the radius of a circle is doubled, then the circumference is also doubled.
True
300
What is (distance around) divided by (radius)?
C/r=2pi
300
What is the circumference of a circle if it has a diameter of 5.2 m?
C=pid=pi(5.2m)=16.33 m
300
A circle has a diameter of 25cm. What is its area?(2 decimal places)
A=pi(12.5)^2= 490.63cm^2
300
Which set does NOT create a circle graph?
1) white- 78%, pink 33%, brown 28%, red 42%
2) white 24%, pink 33%, brown 33%, red 29%
3) white 20%, pink 28%, brown 44%, red 8%
#1 and #2 do not crate a circle graph.
#3 creates a circle graph.
300
When drawing a circle graph, what tools should you use: 1) to measure each section? 2) to draw the circle? 3) to find the radius or diameter?
1) Protractor
2) Compass
3) Ruler
400
What are the equations for finding the radius and diameter?
radius= d ÷ 2
diameter =r x 2
400
If you are given a radius of 6 cm, what is the circumference?
C=2pir=2pi(6cm)=12pi cm
400
The area of a circle is about how many times the square of its radius?
A.1 B.2 C.3 D.4
C.3
400
There are 22 bouncy balls 8 are blue, 10 are red, and 4 are yellow. What is the percent of the BLUE bouncy balls?
8/22=0.36=36%
400
The measure of space covered by a 2-D shape is the definition for _____? Find this if you have a radius of 5 cm.
Area = pi(5cm)^2 = 25pi cm^2 = 78.5 cm^2
500
What is the radius of a circle with a diameter of 95m?
r=d/2=(95m)/2=47.5m
500
What is the diameter of a circle that has a circumference of 221mm? (round to nearest hundredth)
C=pid->d=C/pi=221/pi=70.38 mm
500
Forty-four meters of fencing is used to make a circular enclosure. What is the area of the circle? (to the nearest square meter)
C=2pir -> r=C/(2pi)=(44m)/(2pi)=7 m
A=pi(7m)^2=49pim^2=154 m^2
500
There are 30 students in a grade 7 class. Three people use the internet once a week, 9 people use the internet 3 times a week, 18 people use the internet every day. What percent of the graph is each category of internet use?
Once a week: 3/30=0.1=10%
Three times a week: 9/30=0.3=30%
Everyday: 18/30=0.6=60%
500
The outer circle of the Canadian toonie ($2) has a diameter of 28mm. The inner circle has a diameter of 8mm. What is the area of the outer ring to the nearest hundredth of a square millimeter?
Area of Outer Circle: pi((28mm)/2)^2=615.75mm^2
Area of Inner Circle: pi((8mm)/2)^2=50.27mm^2
Area of Outer Ring: 615.76mm^2-50.27mm^2=565.49mm^2