Posted by Temperance on Monday, June 14, 2010 at 12:59am.
What is the circumference of the circle if the radius is:
5xMy answer was 57(x)pi.
What is the radius if the circumference is:
30x(pi)My answer was 2x.
(x + y)pi My answer (x+y)/7.
What is the length of the arc if:
radius=3 degree of measurement of arc=6 My answer was pi/9.
radius=4 degree of measurement of arc=7 My answer was 9(pi)/18.
radius=2 degree of measurement of arc=x My answer was x(pi)/15.
My answers for these questions were incorrect. I am unsure of how to redo them.Cheers!

Geometry  Reiny, Monday, June 14, 2010 at 6:45am
1. circumf = 2πr
= 2π(5x) = 10πx
2. using the above ...
30xπ = 2πr
r = 30xπ/(2π) = 15x
3. arclength = rØ , where Ø is the central angle in radians
if r=3
if arcangle =6° , then Ø = π/30
(to change ° to radians, multipy your degree unit by π/180) ..... 6(π/180) = π/30
so:
arc = 3(π/30) = π/10
The others in this third part of your post are done the same way