D= absolute value (am+bn+c)/ root number (a 2+b 2), 8, set point M(x0, y0).
The straight line Ax+By+C=0
Distance from m to straight line =|Ax0+By0+C|/√(A? +B？ ), 1, set point M(x0, y0)
The straight line Ax+By+C=0
Distance from m to the straight line under the root sign = | Ax0+By0+C |/(a? +B？ ), 1,