in the figure below the radius of circle p is 6 units.

Given:
The radius of the given circle = 6 unit
P be its center.
Along the arc AB, ∠APB = 111°
Along the arc BC, ∠BPC = 129°
To find the length of the arc ABC.
Formula
The relation between arc length, θ, r as radius is
arc length = [tex]2 \pi r\frac{\theta}{360}[/tex]
Now,
Along the arc ABC, ∠APC = ∠APB+∠BPC
or, ∠APC = 111°+129°
or, ∠APC =240°
Taking,
r = 6, θ = 240° we get,
[tex]arc length ABC = 2\pi (6)\frac{240}{360}[/tex]
or, [tex]arclength ABC = 8 \pi[/tex]
Hence,
The length of the arc ABC is 8π.