A triangle is a polygon having three sides. A vertex of a triangle is a point at which two of the sides meet.

A triangle T can be defined as follows:

from three given points A, B, C.

from three given lines l1, l2, l3.

To access the information relating to a triangle T, use the following function calls:

The command with(geom3d,triangle) allows the use of the abbreviated form of this command.

$\mathrm{with}\left(\mathrm{geom3d}\right)\:$

$\mathrm{point}\left(A\,0\,0\,0\right),\mathrm{point}\left(B\,1\,1\,1\right),\mathrm{point}\left(C\,1\,0\,2\right)\:$

$\mathrm{triangle}\left(\mathrm{T1}\,\left[A\,B\,C\right]\right)$

$\mathrm{T1}$

$\mathrm{form}\left(\mathrm{T1}\right)$

$\mathrm{triangle3d}$

$\mathrm{map}\left(\mathrm{coordinates}\,\mathrm{DefinedAs}\left(\mathrm{T1}\right)\right)$

$\left[\left[0\,0\,0\right]\,\left[1\,1\,1\right]\,\left[1\,0\,2\right]\right]$