Given `a+b+c+d=0`. Which of the following statements(s) is (are) correct?

Options

A. `a,b,c,` and `d` much each be a null vector
B. The magnitude of `a+c` equals the magnitude of `b+d`
C. The magnitude of `a` can never be greater than the sum of the magnitudes of `b,c` and `d`
D. `b+c` must lie in the plane of `a` and `d` if `a` and `d` are not colinear and in the line of `a` and `d` if they are collinear

Answer

B, C, D