# Thread: length of an arc.

1. ## length of an arc.

How to find the length of an arc without using a circle?

2. ## Re: length of an arc.

Originally Posted by hisajesh
How to find the length of an arc without using a circle?
Unless you can expand on that post giving an actual problem in exact form, then your posting is nonsense.

3. ## Re: length of an arc.

Originally Posted by hisajesh
How to find the length of an arc without using a circle?
If the arc is mapped by a differentiable function f(x) from a to b, then arc length is $\displaystyle \int_a^b \sqrt{1+(f'(x))^2}dx$

4. ## Re: length of an arc.

@Plato: How do you measure the size of a rainbow?