Question

A坐标:(1i,2j,1k) B:(2i,1j,-1k),C:(2i,-3j,1k) 如何求三角形ABC的面积

Answer 1

AB=(1,-1,-2k),BC=(0,-4,2)

S=|AB X BC|/2

=||i,j,k||/2

1,-1,-2

0,-4,2

=|(2,-2,-4)|/2

=√6