Definitions
What is a diameter? (Explain or draw it)
The length of a straight line passing through the center of a circle and connecting two points on the circumference.
What is the radius of a circle with a diameter of 20m?
r = 10m
What is the symbol that represents pi? (Draw it)
π
How many formulas are there to find the area of a circle?
only one formula:
A = πr²
How many degrees does a circle have?
360°
How do you find the radius? (Explain or draw it)
Divide the diameter by 2, or measure the center of the circle to the side.
What is the circumference of a circle with a diameter of 4cm? (use 3.14 as pi)
C=πd
C = 12.56cm
Why is a circle not a rectangle or square (quadrilateral)?
Because it isn't made of straight lines.
Is the diameter equal to twice the radius?
yes, it is!
d = 2r
What shapes measure 360°?
circles (and quadrilaterals, like a rectangle)
What is pi?
Pi is the ratio (fraction) of the circumference to the diameter of a circle, or circumference÷diameter
(C / D) and it is irrational.
22/7 or 3.14
What is the area of a circle with a radius of 6?
Use 3.14 as pi
A = πr²
A = 113.04
How many degrees are in two circles?
360 x 2 = 720°
How many sides does a circle have?
NONE: it has no straight lines (undefined!)
How many lines of symmetry do circles have?
Never ending amount: An infinite number
What is circumference?
Circumference is the perimeter of a circle.
You find the circumference by multiplying pi times the diameter.
C = πd
What is the area of a circle with a diameter of 6?
A = πr² (use 3.14 as pi)
A = 28.26
What are the first 6 digits of pi?
3.14159
How many digits are in pi?
A never ending number: infinite!
Is a circle an oval, or is an oval a circle?
Neither
Define "irrational" (Hint: Pi is irrational)
A number that cannot be written as a simple fraction:
- the decimal goes on forever without repeating
- the number never ends
What is the circumference of a circle with a radius of 5? (use 3.14 as pi)
C = 31.40
What fraction best represents pi?
22/7
As Johnny was going to the grocery store to get a pie for Pi Day, there were others walking out. He saw 7 jugglers and a bear, every juggler had 6 cats, every cat had 5 rats, every rat had 4 tiny houses, every house had 3 mouses, every mouse had a spouse. How many in all were going to the grocery store?
Just Johnny.
The others were walking out of the grocery store!
What is another name for a circle?
A flat sphere