A triangle has verticies A(-2.1,3), B(7,8,-4), and C(5,0,2). Determine the area of triangle ABC.
This is actually a question from co-ordinate geometry. If (x1,y1), (x2,y2) and (x3,y3) are the vertices of a triangle then its area = (1/2))(x1(y2-y3)+x2(y3-y1)+x3(y1-y2))
The co-ordinates of the vertices aren't very clear in your Q but assuming that the three points are (-2.1,3),(7.8,-4)& (5,0.2) the area of the triangle is 10.99 sq. units
Ajit