Three consecutive vertices of a parallelogram ABCD are A (6, – 2, 4), B (2, 4, – 8), C (–2, 2, 4). Find the coordinates of the fourth vertex
Let us assume that the coordinates of the fourth vertex D is (x,y,z).
Now, mid-point of diagonal AC = P(6-2/2, -2+2/2,4+4/2)
= P(2,0,4)
Since it is a parallelogram, the mid-point of BD will also be P,
= P(x+2/2,y+4/2,z-8/2)
= P(2,0,4)
Now, let us equate the coordinates of P,
X+2/2 = 2, i.e., x = 2;
Y+4/2 = 0, i.e., y = -4;
Z-8/2 = 4, i.e., z = 16
Therefore, the coordinates of D will be (2,-4,16).