Circle information
Circumfrance
Area
Diameter, Radius, and semi circles
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

Define the radius of a circle.

The distance from the center of a circle to the outside. 

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

Define the diameter of a circle. 

The diameter of a circle is the distance across the center of a circle from one side to the other. 

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

A circle has the diameter of 73cm. What is the radius. 

r = 36.5cm

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.1b.2c.3d.4

3 (Pie is 3.14)

400

If a circle has a circumference of 56.52cm, what is the diameter and radius of the circle? Round to the nearest whole number. 

Diameter: 18cm

Radius: 9cm

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

How many circles with a radius of 3cm can fit in one large circle across the center line with a circumference of 81.64cm. 

4 circles can fit 

(little circles = diameter of 6cm, large circles = diameter of 26cm)

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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