## anonymous one year ago so i got a question when it ask for the diameter of a circle and it gives me the radius do i put for example 7pi or just 7 and im confused with the whole circle/diamerter thing can someone explain please

1. butterflydreamer

Hint: Diameter = 2 * radius

2. butterflydreamer

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3. anonymous

uhh im still lost for example like diameter is 7 wht is the circumference of a circle wht do i put

4. butterflydreamer

ahhhh okay! So do you know what the formula is to find the circumference of a circle? :)

5. anonymous

kinda

6. butterflydreamer

$circumference= 2 \pi r$ Where r = radius. Remember how i said diameter = 2 * radius? this means that d= 2r Therefore you want to find the value of "r" first :) r = 1/2 * d

7. anonymous

like tht for example Suppose the circumference of a circle is 16π. What is its radius?

8. anonymous

this i mean this

9. butterflydreamer

$Circumference = 2 \pi r$ They've told us that the circumference of the circle equals to 16 pi and we want to find the radius right? $Circumference = 16 \pi$ So this means that $2 \pi r = 16 \pi$ Now just solve for "r" (radius)

10. anonymous

soooo 6pi

11. anonymous

o no i mean 8pi

12. butterflydreamer

close but not quite! $2 \pi r = 16 \pi$ Divide both sides by 2 pi $\frac{ 2 \pi r }{ 2 \pi} = \frac{ 16 \pi }{ 2 \pi}$ $r = 8$

13. anonymous

o ok soo i got anotherone Suppose the circumference of a circle is 3π. What is its diameter?

14. butterflydreamer

follow the same pattern. Circumference of a circle formula: $Circumference = 2 \pi r$ We are given the following information: $circumference = 3 \pi$ $\therefore 2 \pi r = 3 \pi$ Divide both sides by 2 pi to find "r". After you find "r", remember that d = 2r. Since we want to find diameter, multiply r by 2.

15. anonymous

3?

16. butterflydreamer

excellent!! :D

17. anonymous

awesome thx and another one a diameter is 12 what is the radius

18. butterflydreamer

no worries :) remember this: DIAMETER = 2 TIMES RADIUS. RADIUS = 1/2 DIAMETER So if d = 2r And we're told d = 12 12 = 2r Solve for r