Answer:
Remember, if
is a basis for a subspace W of
then
is an orthonormal basis of W, where
and
is defined as:

Then, to find a orthonormal basis of
we will find first the
's.



Therefore,
is a ortogonal basis for
. But we need a orthonormal basis. Then is enough find the corresponding unit vector of the ortogonal basis found.

Hence
is a orthonormal basis for
