Baccab formula

In vector analysis, the baccab formula gives the expansion of a vector triple product

$\mathbf {A} \times (\mathbf {B} \times \mathbf {C} )=\mathbf {B} (\mathbf {A} \cdot \mathbf {C} )-\mathbf {C} (\mathbf {A} \cdot \mathbf {B} )$

where the symbol "×" stands for a cross product between two vectors (resulting into a vector) and the symbol "•" stands for an inner product of two vectors (resulting into a scalar).

The name of the formula is because of the mnemonics: "abc = baccab".