## anonymous one year ago how to find the radius and circumfernce in a circle

• This Question is Open
1. Nnesha

formula to find circumference $\huge\rm C= 2 \pi r$ r =radius if the given is diameter then you use $C= \pi d$ remember radius is half of diameter $\large\rm r=\frac{ d }{ 2 }$

2. anonymous

ive seen a problem where it just gives a circle and says find the radius.. how is that possible if it doesn't give anymore info on it?

3. Nnesha

do you have example like what ?

4. Nnesha

post the original question :=)

5. anonymous

6. anonymous

7. Nnesha

hahha thats fine you can use the tool in draw

8. Nnesha

|dw:1443384527525:dw|

9. anonymous

how did you find the radius if it doesn't give any info on the circle

10. anonymous

ok actually here is another problem i have str8 from the review

11. Nnesha

radius is half of diameter and diameter is straight line passing through the center of the circle

12. anonymous

|dw:1443384671583:dw| find the circ and area of each circle. round to nearest 10th

13. Nnesha

yes that's the diameter a line passing through the center now use the formula to find radius i repeat radius is Half of diameter $\huge\rm r=\frac{ d }{ 2}$

14. Nnesha

r=radius d=diameter so you can replace d with 8

15. anonymous

16. anonymous

its 18 sry sloppy

17. Nnesha

oh okay so use the formula i posted above read my first comment

18. anonymous

$9\times \pi \times 9?$

19. anonymous

sry 2 instead of 9 at the front

20. Nnesha

yes right ! $\large\rm 2 \pi 9$

21. anonymous

mind if i give 1 more example?

22. Nnesha

sure!

23. Nnesha

go for it

24. anonymous

oh and how do i find the area? thats also what it asks

25. Nnesha

oh to find area $\huge\rm A= \pi r^2$

26. anonymous

$81\times \pi?$

27. Nnesha

yes right you can use pi but if it says write answer in terms of pi then 81pi is the answer

28. anonymous

ok then 1 more question if you don't mind =D

29. Nnesha

alright

30. anonymous

|dw:1443385350101:dw| find circumference and area

31. anonymous

so circumference is 26

32. Nnesha

try it

33. Nnesha

not just 26

34. anonymous

sry i mean diameter

35. Nnesha

remember it's $\huge\rm C=2 \color{reD}{\pi} r$

36. anonymous

meant diameter is 26

37. Nnesha

yes right diameter is 26 :=)

38. anonymous

$2 \times \pi \times 13?$

39. Nnesha

looks good

40. anonymous

i think i just learned how to get the diameter, circ, and area of a circle =O

41. Nnesha

good ! :=)

42. anonymous

thanks for the help =D

43. Nnesha

np it was my pleasure :=) welcome to openstudy btw

44. anonymous

thanks =D

45. Nnesha

o^_^o