x

y

x_1

y_1

$\mathrm{P}$  

$\mathrm{O}$

x^2+y^2=r^2    

c: x^(2) + y^(2) = 1
A = Point(c)
f = Tangent(A, c)
B: (x(A), 0)
C: (0, y(A))
g = Segment(A, B)
h = Segment(A, C)