The points A(4, 5, 10), B(2, 3, 4) and C(1, 2, -1) are three vertices of parallelogram ABCD.
Let coordinates of D be(x, y, z)
Direction vector along AB is
\(\therefore\) Equation of line AB, is given by
Direction vector along BC is
\(\therefore\) Equation of a line BC, is given by
Since ABCD is a parallelogram AC and BD bisect each other
Coordinates of D are (3, 4, 5).