电脑
Mathematica
Triangle[{{0,0},{0,3},{4,0}}]给出一个实心的三角形,它的三个顶点分别是:{0,0},{0,3},{4,0}。但是,要想画出这个图形,需要用Graphics。
用Area可以计算这个三角形的面积:Area[Triangle[{{0,0},{0,3},{4,0}}]]
用RegionCentroid(区域形心,即重心)可以求出三角形的重心的坐标:RegionCentroid[Triangle[{{0,0},{0,3},{4,0}}]]
在三维空间里面,绘制一个三角形,三个顶点分别是{0, 0, 0}, {3, 0, 0}, {0,2, 2}:Graphics3D[Triangle[{{0, 0, 0}, {3, 0, 0}, {0,2, 2}}]]
它的面积和重心如下:Area[Triangle[{{0, 0, 0}, {3, 0, 0}, {0,2, 2}}]]RegionCentroid[Triangle[{{0, 0, 0}, {3, 0, 0}, {0,2, 2}}]]
把重心和三角形画在一起: u = Triangle[{{0, 0, 0}, {3, 0, 0}, {0,2, 2}}]; c = RegionCentroid[u];Graphics3D[{{Green, u}, {Black, Point[c]}}]
改变三角形的颜色:Table[Graphics3D[{c, Triangle[{{0, 0, 0}, {3, 0, 0}, {0,2, 2}}]}],{c, {Red, Green, Blue, Yellow}}]
FaceForm 和 EdgeForm 可以分别用来指定面和边的样式:Graphics3D[{FaceForm[Pink], EdgeForm[Directive[Thick, Dashed, Blue]], Triangle[{{0, 0, 0}, {3, 0, 0}, {0,2, 2}}]}]
好,就学这么多!