### 11.17.5 Pole and polar: pole polar

Given a circle centered at O, a point A is a pole and a line L is the corresponding
polar if L is the line passing through the inversion of A with
respect to the circle (see section 11.15.7) passing
through the line OA.

The polar command takes as argument a circle C and a
point a.

polar returns and draws the polar of the point a
with respect to C.

Input:

polar(circle(0,1),(i+1)/2)

Output:

The pole command takes as argument a circle C and a
line L.

pole returns and draws the pole of the line L
with respect to C.

Input:

pole(circle(0,1),line(i,1))

Output:

Input:

affix(pole(circle(0,1),line(i,1)))

Output:

1+i