Single line![Line definition](/TrigoCalc/Line2D/Images/line1.PNG)
Two lines intersection![Two lines intersection](/TrigoCalc/Line2D/Images/line2.PNG)
Line most general equation is of the form:
(1)
where A, B and C are any real number and A and B are not both zero. If B ≠ 0 then we can divide
equation (1) by B to obtain the normalized form of a line:
(2)
This is the equation of a line whose slope is:
and
the slope of the line (m) is defined in terms of the inclination
(3)
Note: if the angle α is greater then 90 degrees then the slope is negative.
α (0 - 90) degrees : positive slope
α (90 - 180) degree : negative slope
Necessary condition for two lines to be perpendicular to each other is that their slopes fulfill the
condition:
m1 m2 = − 1
(4)
In order to find the intersection point of two lines we have to solve the system of linear equations
representing the lines. A x + B y = −CD x + E y = −F
then intersection point exists.