Scalar (dot) product of spacial vectors according to the coordinates
$$A\cdot B = x_1\cdot x_2+y_1\cdot y_2+z1\cdot z2$$
x1, y1, z1 - first vector coordinates
x2, y2, z2 - second vector coordinates
x2, y2, z2 - second vector coordinates
Find
It is known that:
= 