## anonymous one year ago find the length of the radius of circle c. http://media.education2020.com/evresources/2092539_2f57b746-c73f-4a4b-8c7e-ce9ee207b927.png

1. anonymous

A. r=1 B. r=3 C. r=12 D. r=15

2. anonymous

@dan815

3. anonymous

@DanJS

4. dan815

okay that angle you see is actually in radians

5. dan815

when they say 4/9 pi they really mean 4/9 pi radius is our angle

6. dan815

that means this angle you see subtends a total of 4/9 pi radius units on the circumference of the circle

7. dan815

$\frac{4}{9}\pi * r =\frac{20}{3} \pi$\

8. anonymous

ohh

9. dan815

yep :) so what is r

10. anonymous

so it would be r=15

11. dan815

yep

12. anonymous

Thank you soo much

13. DanJS

14. anonymous

:)

15. dan815

dont let radians confuse you, its a very simple idea, we are saying the angle in terms of the radius units thats why there are 2pi radians in a circle beacuse the circumference of a circle is 2 pi r

16. anonymous

ok thank you.:)

17. dan815

welcome

18. DanJS

yeah , i was looking for a easy explination that @dan815 just said... http://www.themathpage.com/atrig/arc-length.htm