Asked by Nick

A tringle has vertices a (-1,3,4), b(3,-1,1) and c(5,1,1). What is the abc area
Answered by oobleck
If we let
u = ab = b-a = (4,-4,-3)
v = ac = c-a = (6,-2,-3)
Then the area is
1/2 |u×v| = ____