Consider a tetrahedron with faces `f_1, f_2, f_3, f_4`. Let `vec a_1, vec a_2, vec a_3, vec a_4` be the vectors whose magnitudes arerespectively equal to the areas of `f_1,f_2,f_3,f_4` and whose directions are perpendicular to these faces in theoutward direction. Then

Options

A. `vec(a_(1)) + vec(a_(2)) + vec(a_(3)) + vec(a_(4)) = 0`
B. `vec(a_(1)) + vec(a_(3)) = vec(a_(2)) + vec(a_(4)) `
C. `vec(a_(1)) + vec(a_(2)) = vec(a_(3)) + vec(a_(4)) `
D. none of these

Answer

A