### 26.15.3 Checking whether four points are concyclic in the plane

See Section 27.11.7 for checking for concyclicity in 3D geometry.

The is_concyclic command determines whether or not points are cyclic.

- is_concyclic takes L, a list or sequence of points.
- is_concyclic(L) returns 1 if the points in L all lie on the same circle, and 0 otherwise.

#### Examples

is_concyclic(1+i,-1+i,-1-i,1-i)

1 |  |  |  |  |  |  |  |  |  |

is_concyclic(i,-1+i,-1-i,1-i)

0 |  |  |  |  |  |  |  |  |  |