# Arc: Length

How to find the length of an arc: formula, 1 example, and its solution.

## Formula

l = 2πr⋅[θ/360]

l: Length of an arc

r: Radius

θ: Central angle (in degrees)

2πr is the circumference of the whole circle.

θ/360 is the ratio of arc/circle.

## Exampler = 6, θ = 120º, l = ?

Solution

Solution (Detail)

r = 6

θ = 120º

l = 2π⋅6⋅[120/360]

2π⋅6 = 12π

120/360 = 1/3

12⋅[1/3] = 4

So 4π is the answer.