Question

If a b and c are three unit vectors such that a + b + c = 0 then ab + bc + ca =

Answer 1

Answer:

answer will be 0 because a+b+c=0 each value is 0 so 0+0+0 =0 therefore ab+bc+ca =O because value of a is 0 and value of b is 0 and value of c is also 0 so 0×0+0×0+0×0= 0

Answer 2

Answer:

$- \frac{3}{2}$

Step-by-step explanation:

$(a + b + c) = 0 \\ (a + b + c)^{2} = 0 \\ |a|^{2} + |b|^{2} + |c|^{2} + 2(ab + bc + ca) = 0 \\ 1 + 1 + 1 + 2(ab + bc + ca) = 0 \: \: (|a|,|b|,|c| = 1) \\ 2(ab + bc + ca) = - 3 \\ (ab + bc + ca) = - \frac{3}{2}$