Circle information
Circumfrance
Area
Circle graphs
Ramdom Review
100
What would you use from your protractor kit to make a circle.
Compass
100
What does circumfrance mean?
the distance around a circle (like perimeter of square)
100
What is the equation for the area of a circle?
A = π x r x r
100
How much should all the percents in a circle graph add up to?
100%
100
what is the area of a circle with with a 2.4 radius? (to the nearest tenth)
A=3.14x 2.4 x2.4 A=18.1cm2
200
Show what the radius of a circle and the diameter of a circle is?
Radius- goes from the edge of the circle to the middle of the circle. Diameter- extends from one side of the circle to the other, passing through the center.
200
What is the equation for circumfrance?
c=π x d or c= π x 2 x r
200
If you have a circular mirror with a radius of 20cm, what is it's area?
A= 3.14 x 20x 20cm A = 1256cm
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?
11.2 students have blonde hair
200
true or false: If the radius of a circle is doubled, then the circumfrance is also doubled?
Always true
300
Describe how you would make a circle if you knew the radius was 5cm.
You would take your compass and measure it so it's 5cm wide, and then draw a circle.
300
What is the circumfrance of a circle if it has a diameter of 5.2 m?
answer: 16.3 m c=3.14 x 5.2 c= 16.3 m
300
A circle has a diameter of 25cm. What is it's area?
r=12.5cm A=3.14 x 12.5 x 12.5 A= 490.6cm
300
Which information should not be in a cicle 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%
number 1 and 2 should not be in a circle graph. Number three can be 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) to measure the sections you use a protractor 2) to draw the circle you need a compass 3) to find the radius or diameter you need a 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 6cm, what is the circumfrance?
d= r x 2 d= 12 c=π x d c= 3.14 x 12 c = 37.68 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
This question is a test give away! answer: 3
400
There are 22 bouncy balls 8 are blue, 10 are red, and 4 are yellow. What is the percent and decimal value of the blue bouncy balls? What would the value of its central angle be in a circle graph? (remember there are 360 degrees in a full circle)
8/22 = .36 which is 36 %. central angle = .36 x 360 = 129.6
400
The measure of space covered by a 2 dimentional shape is the definition for what? And Find this if you have a radius of 5cm.
area =78.5 cm2
500
What is the radius for a circle with diameter of 95mm.
47.4 mm
500
What is the diameter of a circle that has a circumfrance of 221mm? (round to nearest hundredth)
c= π x d 221mm = 3.14 x d 221/3.14 =d 70.38mm
500
Fourty four metres of fencing is used to make a circular enclosure. What is the area of the circle? Answer to the nearest square metre.
44 is the circumfrance 44=3.14 x d 14.01= d r=7.01 A= π x r x r A= 3.14 x 7 x 7 A=154 m
500
Draw a circle graph to show the information on internet use from a grade 7 class. There are 30 students in the class. 3 people use the internet once a week, 9 people use the internet 3 times a week, 18 people use the internet every day. (you will need to find the % of total, the decimal value, and the central angle in order to complete this question.)
3- 10%, .10, 36 degrees. 9- 30%, .30, 108 degrees. 18- 60%, .60, 216. The graph is on page 293 of your text.
500
The outer ring of the canadian toonie has an outside diameter of 28mm and an inside diameter of 16mm. What is the area of the outer ring to the nearest hundredth of a square millimeter?
414.48mm2
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