/sci/ - Science & Math

I have the unit circle and two points <span class="math">(x_1,x_2)[/spoiler], <span class="math">(y_1,y_2)[/spoiler] on it. Now I want to convert them in polar coordinates
<span class="math">x_1 = \cos(\varphi_1)[/spoiler]
<span class="math">x_2 = \sin(\varphi_1)[/spoiler]
<span class="math">y_1 = \cos(\varphi_2)[/spoiler]
<span class="math">x_2 = \sin(\varphi_2)[/spoiler]


What is <span class="math">|x-y|[/spoiler] written in those polar coordinates?