The length of CD is √ (m 2+n 2).

In Rt△ACB, CD=AD=BD= 1/2AB= 1.

∴m^2+n^2= 1

This function is an analytical expression of a circle with a radius of 1

While the wooden stick AB wall slides down to the end of A'C= 1m, 1/2.

In the process of sliding, the trajectory of the midpoint of the stick is that the central angle is 30 degrees.

A short arc.

Distance: (30/360)*2πr=π/6