# Math Help - find the distance of the point form the line

1. ## find the distance of the point form the line

point (3,-1,-1),and line is through the points (1,0,-2) and (2,1,-1). We are told to use distance= [(A − P) × u]/[u]. But why do we use cross product here rather than dot product?Thanx

2. Hello,

Originally Posted by Jojo123
point (3,-1,-1),and line is through the points (1,0,-2) and (2,1,-1). We are told to use distance= [(A − P) × u]/[u]. But why do we use cross product here rather than dot product?Thanx
Because the distance from a point to a line is defined as being the length of the perpendicular line to the line and starting at the point..