## anonymous one year ago ques

1. anonymous

$\vec \nabla \times \vec \nabla \times \vec f=\vec \nabla(\vec \nabla . \vec f)-\nabla^2 \vec f$ Can we use vector triple product to prove this identity??Expanding it is long and unecessary :/

2. Michele_Laino

are you familiar with the Ricci's symbol

3. anonymous

Nope

4. Michele_Laino

you can apply this identity: $\Large {\mathbf{a}} \times \left( {{\mathbf{b}} \times {\mathbf{c}}} \right) = \left( {{\mathbf{a}} \cdot {\mathbf{c}}} \right){\mathbf{b}} - \left( {{\mathbf{a}} \cdot {\mathbf{b}}} \right){\mathbf{c}}$

5. anonymous

that's what I am asking if it's ok to use that

6. anonymous

It looks like a quick and cheat method lol

7. Michele_Laino

yes! you have to memorize that identity :)

8. anonymous

alright sweet :D

9. Michele_Laino

:)

10. IrishBoy123

do it!! you're just pattern matching after all and $$\nabla$$ is functionally a vector....

11. anonymous

yeah :P