### 12.16.13 Check if two circles in the plane are orthogonal: is_orthogonal

See section 13.13.5 for checking for orthogonality in three-dimensional geometry.

The is_orthogonal command is a Boolean function which takes as argument two lines or two circles.

is_orthogonal returns 1 if the objects are orthogonal and returns 0 otherwise.
Input:

is_orthogonal(line(0,1+i),line(i,1))

Output:

1

Input:

is_orthogonal(line(2,i),line(0,1+i))

Output:

0

Input:

is_orthogonal(circle(0,1+i),circle(2,1+i))

Output:

1

Input:

is_orthogonal(circle(0,1),circle(2,1))

Output:

0