4th Vertex in a 3D Parallelogram

[Temp0]

Homework Statement

Let P, Q, and R be the vertices of a parallelogram with adjacent sides PQ and PR. Find the other vector S.
P (2, 0 ,-1), Q (-2, 4, 1), R (3, -1, 0)

Homework Equations

PR = QS
PQ = RS

The Attempt at a Solution

I took the two equations and solved both of them, getting (-1, 3, 2) for S by making the coordinates of S into x, y, and z and solving the equations. However, my answer doesn't seem to be correct. Why am I wrong? Thank you in advance.

 

[tiny-tim]

Hi Temp0!

Let P, Q, and R be the vertices of a parallelogram with adjacent sides PQ and PR. Find the other vector S.
P (2, 0 ,-1), Q (-2, 4, 1), R (3, -1, 0)
…
I took the two equations and solved both of them, getting (-1, 3, 2) for S

I don't understand your method, but your result seems correct.

(are you sure it isn't "with adjacent sides PQ and QR"?)

 

[BruceW]

yeah... I get S = (-1,3,2) also.

 

[Temp0]

Hi Temp0!


I don't understand your method, but your result seems correct.

(are you sure it isn't "with adjacent sides PQ and QR"?)

Just checked, nope, PQ and PR... I think it might be a mistake in the book ;_;