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
What is square root of 121?
11
what is the area of a circle with a 2.4 cm radius? (to the nearest tenth)
A=3.14x 2.4 x2.4 A=18.1cm^2
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 C = 14pi, how long is the radius?
7 units
true or false: If the radius of a circle is doubled, then the circumference is also doubled?
Always true
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
The diameter of a circle is 12meters. What is circle's area?
36 m2
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
The area of a circle is 25pi km2. What is the circle's circumference?
10pi km
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
You want to fi nd the distance the monster truck travels when the tires make one 360-degree rotation. What best describes this distance?
circumference