A = (-8,4,2) not (-8,4,-2) as you've written when calculating |AB| and |AC|Greeting MathHelpForum,

I'm currently working through grade 12 Calculus and Vectors in an independent-learning course. I've just recently finished the calculus portion of the course, finding it relatively painless on the whole, and so I assumed the vector portion would be a walk in the park, especially since I've done some work with vectors in grade 12 physics. That does not seem to be case however; I've had a few questions now that have stumped me for quite a while, and I really can't seem to wrap my head around this one in particular. I don't have any teachers or instructors for this course than I can go to for help, so if anyone here could point out where I'm going wrong it would be greatly appreciated. The question is as follows:

The vertices of a figure are given by A(-8, 4, 2), B(-6, 3, 5) and C(-10, 5, -9). What type of figure is ABC? Justify your answer. (Hint: Calculate the magnitudes of the sides of the figure.)

and here is my attempt at an answer:

AB = (-8, 4, -2) – (-6, 3, 5) = (-2, 1, -7)

|AB| = √[(-2)^{2}+ (1)^{2}+ (-7)^{2}] = √(54) ≈ 7.35

fix this and redo it.