Mathematics

Problem

Let us define the length of a vector

a\hat{i} + b\hat{j} + c\hat{k}

|a| + |b| + |c|

. This definition coincides with the usual definition of length of a vector

a\hat{i} + b\hat{j} + c\hat{k}

if and only if a.

a = b = c = 0

b. any two of

a, b

and

c

are zero c. any one of

a, b

and

c

is zero d.

a + b + c = 0