Posted by Muja on .
show that the quadrilateral with vertices at the following points is a parallelogram and find its area. a = (5,2,0), b = (2,6,1), c = (2,4,7), d = (5,0,6)

College Math 
Steve,
AB has direction (3,4,1)
BC has direction (0,2,6)
CD has direction (3,4,1)
DA has direction (0,2,6)
So, AB  CD
and BC  AD
since the sides are parallel in pairs, they must have the same lengths in pairs (I trust you can verify this).
the area is just
(ba)x(da)
where a,b,c,d are the vectors to the points A,B,C,D. 
College Math 
Muja,
thanks steve. u really help me out.. really appreciate it .. =)