Question

Which circles have a circumference of units?



Choose all answers that are correct.



A.


a circle with a diameter of 40 units


B.


a circle with a radius of 10 units


C.


a circle with a diameter of 20 units


D.


a circle with a radius of 20 units

Im think A C and D but i really don't know this one

Answer 1

@geerky42

Answer 2

@zepdrix

Answer 3

im looking at pics of a circumference and now i think its B

Answer 4

"Which circles have a circumference of units"

how much units?

Answer 5

well idk because there is no picture for me to see

Answer 6

there is no picture...

Answer 7

@UsukiDoll

Answer 8

Your question is missing something.

Answer 9

Gabby you'll need to be more specifi with the question. @geerky42 could you help me please?

Answer 10

Which circles have a circumference of __?__ units

Answer 11

well thats all it says ill take a screenshot

Answer 12

@geerky42

Answer 13

Gabby you missed the Pi there, that's very important =)

Answer 14

oh

Answer 15

ooooooooh

Answer 16

So circumference = 2*radius * pi. And diameter = 2 * radius.
So circumference also = diameter * pi

Can you solve it now?

Answer 17

so 4pi

Answer 18

?

Answer 19

So let's look at (a). If d = 40. What is d * pi? Does that equal 20 * pi?

Answer 20

no

Answer 21

Very good. Can you do the same for (b) now?

Answer 22

b is not correct either so now its just C and D

Answer 23

I think D

Answer 24

because it needs a radius

Answer 25

b is correct. let's go through it carefully. Remember, diameter is radius * 2. So you must multiply that 10 by 2.

Answer 26

oooooh i see what you're going at

Answer 27

diameter can be converted to radius (d = 2*r). Also, radius can be converted to diameter (r = d/2)

Answer 28

Okay, I get it now. Thank you! √

Answer 29

No problem! Good luck =)

Answer 30

It was B and C. Thanks for your help though. :)

Answer 31

yep, that's right.