Introduction to Circles

Keep track of these notes. We will add to them every few days.

​

Geometry

​Parts of a circle

​Add the following information to your notes:

Multiple Choice

To determine the length of the hand on the clock, you would need to find...

• diameter

• radius

• circumference

• area

Multiple Choice

To determine the distance around the clock you would need to find...

• diameter

• radius

• circumference

• area

Multiple Choice

To find the amount of grass seed needed to cover the garden, you would need to calculate

• diameter

• radius

• circumference

• area

Multiple Choice

To find the length of fence required to go all the way around the garden, you would need to calculate

• diameter

• radius

• circumference

• area

Multiple Choice

To find the length of a slice of pizza, you would need to calculate

• diameter

• radius

• circumference

• area

Multiple Choice

To find the distance across the pizza, you would need to calculate

• diameter

• radius

• circumference

• area

Multiple Choice

To find the amount of glass needed to cover the mirror, you would need to calculate

• diameter

• radius

• circumference

• area

Multiple Choice

To find the length of decorative edging around the mirror, you would need to calculate

• diameter

• radius

• circumference

• area

Multiple Choice

To find the distance across the ferris wheel, you would need to calculate

• diameter

• radius

• circumference

• area

Multiple Choice

To find the length of the support beam, you would need to calculate

• diameter

• radius

• circumference

• area

Multiple Choice

To find the length of blue cover padding, you would need to calculate

• diameter

• radius

• circumference

• area

Multiple Choice

To find the amount of fabric canvas to make the trampoline, you would need to calculate

• diameter

• radius

• circumference

• area

​Parts of a circle

Back to your notes:

• ​What does this mean?

  • When you see the π symbol in a formula or answer, this is the EXACT value. (Because you haven't rounded pi to 3.14)

​We have lots of different approximations for pi. Since π never ends and never repeats, everybody could be using a different version of pi. That's not very exact is it?

​Flip over to the back of your notes

​Fill in the information pictured here

​Pause and think about WHAT you are writing. You will have to do this on your own next. Do you understand where each step comes from?
The diameter is 2 times the radius. If the radius is 7, then 7 x 2 = 14. Therefore, the diameter is 14 cm.

​Fill in the information pictured here

Read carefully. These are the steps I followed. You need to fully understand each step pictured, so that you can do this on your own.

Read carefully. These are the steps I followed. You need to fully understand each step pictured, so that you can do this on your own.

​Fill in the information pictured here

Read carefully. These are the steps I followed. You need to fully understand each step pictured, so that you can do this on your own.

Read carefully. Your turn is next.

Multiple Choice

What was the exact circumference?

(Be careful. You need DIAMETER to find circumference. Do you have the diameter yet?)

• $$100\pi\ m^2$$

• 314 m

• $$20\pi$$ m
  

• 62.8 m

Multiple Choice

What is the approximate circumference?

• 10 m

• 31.4 m

• $$20\pi$$ m

• 62.8 m

Multiple Choice

What is the exact area?

• $$20\pi$$ m

• 62.8 m

• $$100\pi\ m^2$$

• $$314\ m^2$$

Multiple Choice

What is the approximate area?

• $$20\pi$$ m

• 62.8 m

• $$100\pi\ m^2$$

• 314  $$m^2$$  

Multiple Choice

What is the exact circumference?

• $$8\pi$$ km

• 25.12 km

• $$16\pi\ km^2$$

• 50.24 km

Multiple Choice

What is the approximate circumference?

• $$8\pi$$ km

• 25.12 km

• $$16\pi\ km^2$$

• 50.24 km

Multiple Choice

What is the exact area?

(Be careful, you need RADIUS for area. Find that first.)

• $$8\pi$$ km

• 25.12 km

• $$16\pi\ km^2$$

• 50.24 km

Multiple Choice

What is the approximate area?

• $$8\pi$$ km

• 25.12 km

• $$16\pi\ km^2$$

• 50.24 $$km^2$$