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kingwinner
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Homework Statement
Let S is a (hyper)surface defined by {x|F(x)=0}. Suppose n1 and n2 are both normal to S at x=a. Then n1 and n2 are scalar multiples of each other.
Homework Equations
The Attempt at a Solution
If S is a surface in R3, then I think it's clear geometrically that the above must be true in this case. But what about in higher dimensions (hypersurface)? Is the above still true? If so, how can we prove it? I really can't think of a sound way of justifying it. Or is the above only true for a surface in R3?
Thank you for answering.