Theorem
Given sets of reciprocal vectorsandthen any vectorcan be written in terms of
Proof
Use the identityand rearrange it to givevec u cdot (vec v times vec w ) =vec w cdot (vec u times vec v )= vec v cdot (vec u times vec v ) hence(1)
From the definitions of vec a' , vec b' , vec c',we can write (1) as