(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The following are all vectors:

a, b, c, d

k = (a+b) (c+d)

prove: k = (a x c) + (a x d) + (b x c) + (b x d)

2. Relevant equations

3. The attempt at a solution

I have tried to start it by doing:

|a| = a = sqrt(a_x^2 + a_y^2)

is that a correct start at it? I really am pretty lost...

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# How can I solve this proof?

**Physics Forums | Science Articles, Homework Help, Discussion**