13.13.10 Check if an object in space is an isosceles triangle: is_isosceles
See section 12.16.6 for checking for isosceles
triangles in two-dimensional geometry.
The is_isosceles command takes as argument either three
points or a geometric object.
is_equilateral returns 1, 2, 3 or
4 is the points are the vertices of an isosceles triangle or
if the object is an isosceles triangle, and returns 0
otherwise. Specifically,
-
It returns 4 if the object is an equilateral triangle
or if the points are the vertices of an equilateral triangle.
- It returns 1, 2 or 3, respectively,
if the object is an isosceles triangle or if the points are the
vertices of an isosceles triangle and the first, second or third
point is the vertex with equal sides.
Input:
is_isosceles([2,0,0],[0,0,0],[0,2,0])
Output:
2
Input:
T := triangle_isosceles([0,0,0],[2,2,0],[2,2,2])
then:
is_isosceles(T)
Output:
1
Input:
is_isosceles([1,1,0],[-1,1,0],[-1,0,0])
Output:
0