# Vectors 2

1. Feb 26, 2010

### icystrike

Multiple post

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Last edited: Feb 26, 2010
2. Feb 27, 2010

### gabbagabbahey

It's not clear to me what your method is here, but your result doesn't seem correct.

Your result contains the point (3,0,1) and also (just picking a random point in the plane) (1,2,1); and therefor the vector (3,0,1)-(1,2,1)=(2,-2,0) is parallel to your plane.

Now, the plane $\Pi_1$ contains the points (1,-1,7) and (0,-7,0), so the vector (1,-1,7)-(0,-7,0)=(1,6,7) is parallel to $\Pi_1$.

If your plane were really perpendicular to $\Pi_1$, then any vector parallel to your plane would be perpendicular to any vector parallel to $\Pi_1$ and hence you would expect $(2,-2,0)\cdot(1,6,7)$ to be zero; but it clearly isn't.

If you explain your reasoning for each step, and state your reults for parts (i) through (iii), I may be able to see where you are going wrong. A jumbled mess of equations, without any explanation is not a solution.