Checking if three points are collinear in the plane: is_collinear

### 13.16.2 Checking if three points are collinear in the plane: is_collinear

See Section 14.13.6 for checking for collinearity in three-dimensional geometry.

The is_collinear command determines whether or not three points are collinear.

- is_collinear takes three arguments:
  A,B,C, three points.
- is_collinear(A,B,C) returns 1 if A,B and C are collinear and returns 0 otherwise.

#### Examples.

- Input:
  is_collinear(0,1+i,-1-i)
  Output:

  1

- Input:
  is_collinear(i/100, 1+i, -1-i)
  Output:

  0