26.15.7 Checking whether an object in the plane is a right triangle or a rectangle
See Section 27.11.11 for checking for right triangles and
rectangles in 3D geometry.
The is_rectangle
command determines whether or not a geometric object is a rectangle or right triangle.
-
is_rectangle takes
G, a geometric object or a sequence of three or four points
assumed to be the vertices of a triangle or a quadrilateral.
- is_rectangle(G) returns:
-
(for triangle G) 1, 2 or 3 if G is a right
triangle (the number indicates which vertex has the right angle).
- (for quadrilateral G) 1 if G is a rectangle but not a
square.
- (for quadrilateral G) 2 if G is square.
- 0 otherwise.
Examples
| is_rectangle(1+i,-2+i,-2-i,1-i) |
| R:=rectangle(-2-i,1-i,3,C,D); is_rectangle(R[0]) |
Note that R[0] is a rectangle since R is a list made
of a rectangle and vertices C and D.