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# 4.1 Distances

The distance between two points in the plane is the length of the line segment joining the two points. If the points have cartesian coordinates (x ,y ) and (x ,y ), this distance is If the points have polar coordinates (r ,  ) and (r ,  ), this distance is If the points have oblique coordinates (x ,y ) and (x ,y ), this distance is where is the angle between the axes (Figure 1.5.1 ).

The point k% of the way from P =(x ,y ) to P =(x ,y ) is (The same formula works also in oblique coordinates.) This point divides the segment P P in the ratio k:(100-k). As a particular case, the midpoint of P P is given by

(½(x +x ), ½(y +y )).

The distance from the point (x ,y ) to the line ax+by+c=0 is Next: 4.2 Angles
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Silvio Levy
Wed Oct 4 16:41:25 PDT 1995

This document is excerpted from the 30th Edition of the CRC Standard Mathematical Tables and Formulas (CRC Press). Unauthorized duplication is forbidden.