Question

Help with three multiple choice geometry questions? (Questions Inside) [Will MEDAL & FAN]

Answer 1

@robtobey quick help?

Answer 2

For the first one area of a circle is (pi)r^2,
What is the radius of the circle?

Answer 3

The radius would be 10

Answer 4

So in put 10 and you would get \[\pi10^2\]

Answer 5

Solve that and you would get the answer

Answer 6

For the second one, what is the area of the circle?

Answer 7

63 square Feet for the first one

Answer 8

Umm no,
10^2=100
100*pi=?

Answer 9

Oh ok I see. It's 314 Square Feet.

Answer 10

Yes.

Answer 11

#3
\[\pi r^2=4 (36 \pi ) \]
Solve the above for r.

Answer 12

So for the second one what is the area of the entire circle?

Answer 13

would I do Pi12^2?

Answer 14

Yes

Answer 15

So 12^2=144
then 144*Pi?

Answer 16

Yes, go ahead and get a decimal approximation for that because none of the answers are in terms of pi

Answer 17

Oh ok I got 452.16

Answer 18

Yep

Answer 19

So after that it is saying that the triangle is split up into 20 equal segments, and it is asking for the area of ONE of them, so it is asking for the area of 1/20 of the circle how would you do that?

Answer 20

452.16 Divided by 20-- 22.608

Answer 21

22.6 Square mm

Answer 22

Yes

Answer 23

Lets move onto three

Answer 24

Umm in my opinion robtobey's answer is pretty good to solve, do you need an explanation to how he got there?

Answer 25

um no, I'd solve 4(36pi) right

Answer 26

For #3
A circle has 360 degrees all around.
A 90-degree sector is 90/360 = 1/4, or one quarter of the circle's area.
You are told that a 90-deg sector has and area of 36pi.
That means the full circle has an area of 4 * 36pi = 144pi

Answer 27

What you have, 36*pi*4 = 144pi, is the area of the full circle.

Answer 28

The area of a circle is \( \pi r^2 \)
Your circle has area \(144 \pi\)

That means that \(\pi r^2\) must equal \(144 \pi\)

\(\pi r^2 = 144 \pi\)

This is the equation robtobey wrote above.
Now solve the equation for r to find the radius of the circle.

Answer 29

First divide both sides by pi to cancel out pi.

Answer 30

Oh ok I see now. 12^2=144 after you cancel out pi. The answer is 12 inches

Answer 31

No.
Don't multiply by pi.
You have pi on both sides of the equation.
Divide both sides by pi.

Answer 32

Good. You got it.

Answer 33

lol I was wondering why you put "no" but thanks for the help.

Answer 34

\(\pi r^2 = 144 \pi\)

\(\dfrac{\pi r^2}{\pi} = \dfrac{144 \pi}{\pi}\)

\(r^2 = 144\)

\(r = \sqrt{144}\)

\(r = 12\)

Answer 35

I type slowly.

Answer 36

You're welcome.

Answer 37

Thank you @mathstudent55 , my fault I left without warning