## anonymous 4 years ago If arc AB measures 155°, what is the length of the radius of the circle, to the nearest hundredth? drawing pic now.

1. anonymous

|dw:1342078364411:dw|

2. anonymous

Arc Length = Radius * Plane Angle Angle must be in radians

3. anonymous

can you help me out . i dont understand

4. anonymous

-.-

5. anonymous

Convert your angle to radians first. Do you know the formula for that?

6. anonymous

I'm here for you, it's not as bad as it looks.

7. anonymous

no thats the problem

8. anonymous

Ok, the conversion for degrees to radians is: $Angle*\pi/180$

9. anonymous

155*pi/180 ?

10. anonymous

Correct.

11. anonymous

2.705260341

12. anonymous

Okay, now solve the Arc Length formula for radius

13. anonymous

?

14. anonymous

Solve the initial formula for radius: Arc Length = radius * angle

15. anonymous

486.9468613 = 2.705260341* 180 ?

16. anonymous

Hold on, I think you're a little confused still. We know the Arc Length: That was given in your drawing as 14cm We know the angle (that you converted to radians) as 2.705260341 What we're looking for is the radius of the circle that fits those conditions. We can use the formula that I have you to find any single piece of the info that we're missing if we're given the other two.

17. anonymous

i dont understand this at alll

18. anonymous

Let's call the Arc Length S and the Radius R and the Angle A. So: S=RA Divide through by A to get: S/A = R So the radius of the circle (R) is equal to the arc length (S) divided by the Angle in radians (A)

19. anonymous

can yu do for me?

20. anonymous

R = (14)/(2.705260341)

21. anonymous

So R = ?

22. anonymous

37.87364477 ?

23. anonymous

When I divide 14 by 2.705260341, I'm getting 5.175. Rounded to the nearest tenth, that should be 5.2

24. anonymous

oh whoops i accidentally mult instead of divide

25. anonymous

so the answer is 5.175102665 ?

26. anonymous

Yes, don't forget to round to the nearest tenth though.