m_x = -1 (slider from -10 to 10, step 0.1)
m_y = 2 (slider from -10 to 10, step 0.1)
r = 4 (slider from 0 to 20, step 0.1)
M: (m_x, m_y)
K = Circle(M, r)
A = Point(K)
Radius = Segment(A, M)