Question

For points \[P(x_1,y_1,z_1)\] and \[Q(x_2,y_2,z_2)\], which expression gives \[PQ\]?

Options

• \[PQ=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2+(z_2-z_1)^2}\]

• \[PQ=(x_2-x_1)+(y_2-y_1)+(z_2-z_1)\]

• \[PQ=\sqrt{x_1^2+y_1^2+z_1^2}\]

• \[PQ=\sqrt{x_2^2+y_2^2+z_2^2}\]

Answer 1

The distance \[PQ\] is the square root of the sum of the squared coordinate differences. It is used to normalize the direction ratios into direction cosines.