(x,y)=%v

r=%v

θ = 1 rad (slider from 0 to 6.28, step 0.01)
r = 4 (slider from 0 to 7.5, step 0.1)
B = Intersect(xAxis, yAxis)
P = (2.161209223472559, 3.365883939231586)
a = Segment(B, P)
α = Angle(xAxis, a)