Circle information
What would you use from your protractor kit to make a circle?
Compass
What does circumference mean?
the distance around a circle (like perimeter of square)
What is the equation for the area of a circle?
A = pi x r x r
How much should all the percents in a circle graph add up to?
100%
What is (distance around) divided by (diameter)?
Pi
What is the equation for circumference? (both equations)
c=pi x d or c= pi x 2 x r
If you have a circular mirror with a radius of 20cm, what is its area?
A= π x 20x 20cm A = 400π cm2
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 or 12 students have blonde hair
What is (distance around) divided by (radius)?
2pi
A circle has a diameter of 25cm. What is it's area?(2 decimal places)
r=12.5cm
A=π x 12.5 x 12.5
= 490.63cm2
Which information should not be in 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%
number 1 and 2 should not be in a circle graph. Number three can be a circle graph.
What are the equations for finding the radius and diameter?
radius= d ÷ 2 diameter =r x 2
If you are given a radius of 6cm, what is the circumference?
12π cm
The area of a circle is about how many times the square of its radius? a.1 b.2 c.3 d.4
answer: 3
What is the radius of a circle with a diameter of 95m? (leave your answer in cm)
4750 cm
What is the diameter of a circle that has a circumference of 221mm? (round to nearest hundredth)
c= π x d 221mm = 3.14 x d 221/3.14 =d d=70.38mm
Fourty-four metres of fencing is used to make a circular enclosure. What is the area of the circle? (to the nearest square metre)
44 is the circumference
44=3.14 x d 14.01= d r=7.01 A= π x r x r A= 3.14 x 7.01 x 7.01 A=154 m2