How can you find the length of the arc formed by two points on a circle? Is there any function that draws a perfect semi-circle so you can use integrals to find the value of the arc or is there a simpler solution?
Finding arc length
2
$\begingroup$
trigonometry
1 Answers
3
Do you know the angle formed by those two points and the center of the circle? If so, and that angle is $\theta$ in radians, and the radius of the circle is $r$, then the arc length is $$ s = r \theta.$$
Read more here.
Edited:
If you don't know $\theta$, you can find it by taking the dot product of the vectors from the center to each point. More on the dot product here.
-
0No, the angle is what I need to find. I know the radius however. – 2011-04-09
-
0@Paul What *do* you know about the points? Their coordinates, or something else? – 2011-04-09
-
0Their coordinates and the radius of the circle. – 2011-04-09
-
0@Paul So, is my addition helpful? – 2011-04-09
-
0Yes, thank you! :) – 2011-04-09