# Math Help - Plane through 3 given Points

1. ## Plane through 3 given Points

Hi everyone.
I've got this question about finding the plane equation that goes through:
A=(-1,2,0) B=(1,2,0) C=(0,3,-1)

So shall i use the cross product as ABxAC or CAxCB as C is perpendicular to A and B?

Thank you

2. They are one and the same thing

their cross product will yield a vector perpendicular to the plane which is same...

Its CAxCB = ABxAC = 2j + 2b

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3. Originally Posted by Snowboarder
Hi everyone.
I've got this question about finding the plane equation that goes through:
A=(-1,2,0) B=(1,2,0) C=(0,3,-1)

So shall i use the cross product as ABxAC or CAxCB as C is perpendicular to A and B?

Thank you
As Adarsh said, both cross products will give the same plane- $\vec{u}\times\vec{v}= -\vec{v}\times\vec{u}$- they are vectors pointing in opposite directions and so perpendicular to the same plane.

But please don't say "C is perpendicular to A and B". A, B, and C are points, not lines or vectors and so are not perpendicular to anything.