Question

If the area of a circle is 36π square feet, what is the radius, in feet?

Answer 1

Do you know the formula to finding the area of a circle?

Answer 2

a=πr^2

Answer 3

Great. We know that the area of a circle is 36π. So we can plug that in our equation! \[\large \large r^2\pi = 36 \pi\] Make sense so far?

Answer 4

yes

Answer 5

Great! Now what's pi divided by pi give us?

Answer 6

pi squared

Answer 7

Not quite. pi multiply by pi give us pi squared.
We're doing pi divided by pi.
What do you think it is now?
TIP: The 2 pi have the same value.

Answer 8

its just pi

Answer 9

Hmm. We know that pi and the other pi has the same value.
So if we have the same value, divided by the same value, then what does it give us?
Example: 10 / 10 = ?
2.10 / 2.10 = ?

Answer 10

o so its 9π

Answer 11

o.o?
Nope.
Solve my example please:
10 / 10 give us?
2.10 / 2.10 give us?

Answer 12

they both 1

Answer 13

Yes! Now any value divided by the same value will always equal 1, except special circumstances.

So what do you think pi divided by pi give us?

Answer 14

pi

Answer 15

Nooo!
Pi is about 3.14.
So what's 3.14 divided by 3.14 give us?

Answer 16

pi which = 3.14

Answer 17

Pi is appx. 3.14.
We just rounded, but it's still the same.

So what's 3.14 / 3.14 give us?

Answer 18

Fine. Lets round it even more. What's 3 / 3 give us?

Answer 19

3.14/3.14=1

Answer 20

Good! So pi divided by pi cancel out. Now we have: \[\large \large r^2 = 36\]
Now how can we get r by itself?

Answer 21

divide

Answer 22

Divide what?

Answer 23

by r

Answer 24

Hmm. What will it give us?

Answer 25

idk

Answer 26

We can't divide. Do you know what's the opposite of square is?

Answer 27

is the answer 6π

Answer 28

What?!?!?! Nooo!
Pi is gone!

Answer 29

We have r^2 = 36
There's no pi in this equation, so we don't need to worry about pi.

Have you ever heard of square root?

Answer 30

so its either 6 and yes

Answer 31

What's the square root of r^2?

Answer 32

\[pir ^{2}=36\pi then r=6\]

Answer 33

The answer is not just 6. But it's close. :)

Answer 34

e.e.