If the projections of a line of length d on the coordinate axes are d1,d2, d3 respectively, thend12+d22+ d32−d2=
d2
1
0
None
If d1,d2,d3are the projections of a line segment of length don the coordinate axes then d2=d12+d22+d32
Therefore, d12+d22+ d32−d2=0