I don't know if I'm doing this proof right. But, there are 2 ways to figure out an arc length of a circle s=rθ, and finding the circumference of a circle and multiplying that by the ratio of the angle of the arc/360.

So here is my proof, let's start out with the latter method of finding the arc length.

1. 2*π*r((θ*(180/π))/360) = s

Ok, the part where I take theta and multiply by 180/π is to convert degrees to radians. And then I take that and divide by 360 degrees.

2. 2*π*r(θ*(180/π)*1/360) = s

3. 2*π*r(θ*(1/2π)) = s

4. 2*π*r(θ/2π) = s

5. 2*π*r*θ/2π = s

6. r*θ = s

So, that's my proof. Is there something wrong with the proof?

Circumference * ratio of angle arc/360