Math Help - vectors: right triangle

1. vectors: right triangle

Use vectors to show that A(2,-1,1), B(3,2,-1), and C(7,0,-2) are vertices of a right triangle.

2. Originally Posted by jmedsy
Use vectors to show that A(2,-1,1), B(3,2,-1), and C(7,0,-2) are vertices of a right triangle.
$AB = (1,3,-2)$

$BC = (4,-2,-1)$

$AB \cdot BC = 4 - 6 + 2 = 0$

what's that tell you?

3. ab and bc are orthogonal. there is a right angle at vertex b