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#1 2008-04-25 21:11:49
- ROBBYM
- Member
- Registered: 2008-04-24
- Posts: 10
calculus
S is a sphere
i'm suppose to find the unit normal to S but i'm not sure how this is done does anyne know a formula??? please help me 
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#2 2008-04-25 23:01:51
- luca-deltodesco
- Member
- Registered: 2006-05-05
- Posts: 1,470
Re: calculus
to find the normal to a function, take the partial derivitives and normalise the result, first express it in the form f(x..) = 0
which gives the non-unit normal of
which normalised gives
which from the equation for the sphere is simply
Last edited by luca-deltodesco (2008-04-25 23:02:00)
The Beginning Of All Things To End.
The End Of All Things To Come.
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#3 2008-04-25 23:50:21
- JaneFairfax
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- Registered: 2007-02-23
- Posts: 6,868
Re: calculus
Any nonzero vector in
is normal to the surface of an origin-centred sphere.The set of all unit normals to S is therefore the set of all vectors in
with unit modulus.Offline