ax + by + c = 0

r = r₀(1– t) + r₁t, де r=(x, y), t∈ [0, 1]

x(t)= r(t – sint), y(t)= r(1 – cost), t ≥ 0

p(t) = (r₀+r)(sint, cost) – r(sinwt, coswt), w = (r₀/r+1)

p(t) = (r₀– r)(sint, cost)+r(–sinwt, coswt), w = (r₀/r – 1)