# Exam question t/f 2

## Homework Statement

I just remembered another question that I wasn't to sure about

1) if n1xn2 does not intersect the plan then n1xn2=0
I chose false for this one.

thoughts?

## The Attempt at a Solution

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What are n1 and n2, and what is "the plan"?

Plane* sorry, n1, and n2 and vectors.

What plane is this? n1 x n2 is a vector, and for any given vector there are infinitely many planes it does not intersect.

Its a true or false question, don't know what else to tell you.

What is "the" plane in the question? Or was that really "a" plane?

Mark44
Mentor
I'm guessing that n1 and n2 are vectors in the plane, and "intersect" means that it (n1 x n2) intersects at a single point.

Indeed Mark.

LCKurtz
Homework Helper
Gold Member
Its a true or false question, don't know what else to tell you.
You could tell us the complete and exact wording of the question. I have read up through post #8 and I still have no idea what this is about.

Honestly that is exactly how the question was worded.

Mark44
Mentor
Since you're going by what might be an imperfect memory of the problem statement, let's assume that it was as I said.

IOW, n1 and n2 are vectors in a plane. If n1 X n2 does not intersect the plane at a single point, then n1 X n2 = 0.

Ugggg why put true or false on a math exam....

LCKurtz
What a poorly worded question then. Vectors don't intersect planes. Lines with the given vector as a direction vector might. It would better be stated as the contrapositive: If $\vec n_1 \times \vec n_2 \ne \vec 0$ a line with that direction vector intersects the plane in exactly one point.