- #1
Bipolarity
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Homework Statement
If [itex] (a \times b) \times (c \times d) = 0 [/itex], show that a,b,c,d are coplanar.
Homework Equations
The Attempt at a Solution
I have done the converse of this problem, but am having trouble on how to do this. Can we perhaps use Lagrange's identity. How can I start?
BiP