Math Is Fun Forum

owenflo

Member

Registered: 2014-07-21

Posts: 115

Circles: Circumference and Arc Length

What is the radius if the circumference is:

6. 30x(pi) - I chose F

A11x
B21x
C78x
D18x
E 2x
F 15x

7. 4x-10pi

A(3x/pi) - 4
B(2x/pi) - 5
C(7x/pi) - 9
D(6x/pi) - 11
E (5x/pi) - 10
F (4x/pi) - 7

8. (5/2)pi

A(5/4)
B(8/3)
C(6/1)
D(9/4)
E (6/7)
F (10/7)

9. 14pi

A7
B13
C20
D5
E 8
F 10

10. (x + y)pi - I chose D

A(x+y)/7
B (x+y)/5
C(x+y)/1
D(x+y)/2
E (x+y)/3
F (x+y)/8

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Circles: Circumference and Arc Length

Did you leave out a / in question 10?

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

owenflo

Member

Registered: 2014-07-21

Posts: 115

Re: Circles: Circumference and Arc Length

no

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Circles: Circumference and Arc Length

6) F is correct.

7) B

9) A

10) D is correct.

Can you get 8 on your own?

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

owenflo

Member

Registered: 2014-07-21

Posts: 115

Re: Circles: Circumference and Arc Length

8) A

What is the length of the arc if:

11. r=10 n=20

A15(pi)/ 7
B13(pi)/ 5
C16(pi)/ 2
D11(pi)/ 4
E 10(pi)/ 9
F 9(pi)/ 4

Can you help me with this one please

owenflo

Member

Registered: 2014-07-21

Posts: 115

Re: Circles: Circumference and Arc Length

I know that the formula is L=(n/360)(2(PI)r)

owenflo

Member

Registered: 2014-07-21

Posts: 115

Re: Circles: Circumference and Arc Length

13. r=4 n=7

A8(pi)/55
B 6(pi)/12
C7(pi)/45
D2(pi)/22
E 9(pi)/18
F 7(pi)/37

14. r=2 n=x

Ax(pi)/15
Bx(pi)/30
Cx(pi)/60
Dx(pi)/90
E x(pi)/120
F x(pi)/150

math9maniac

Member

From: Tema

Registered: 2015-03-30

Posts: 443

Re: Circles: Circumference and Arc Length

The correct answers are:
13) C

14) D

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Only a friend tells you your face is dirty.

gucci_venus

Member

Registered: 2020-05-07

Posts: 2

Re: Circles: Circumference and Arc Length

What is the circumference of the circle if the radius is:
3x-4

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 48,413

Re: Circles: Circumference and Arc Length

Hi,

Radius, r = (3x-4).
Circumference =

Here,

= The ratio of circumference of a circle and its diameter.

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It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.