Question

Prove that (a-b) x (a+b)=2a x b is true. (a and b are vectors)

Answer 1

(a-b)*(a+b)= a*a + a*b - b*a - b*b

as

a*a = 0 and b*b = 0



-b*a=a*b then

(a-b)*(a+b) = a*b +a*b = 2(a*b)