 Distance between two points p(x1,y1) and Q(x2,y2) is given by
 The coordinates of the mid point of the line joining p(x1,y1) and
Q(x2,y2) are
 The area of a triangle whose vertices are A(x1y1) B(x2y2) and
C(x3y3) is given by
Three points A ( x_{1} y_{1}), B (x2 y2) and C(x3 y3) are collinear if x_{1} ( y_{2}  y_{3}) + x2 (y3  y1) + x3 ( y1  y2 ) = 0  The coordinates of the point dividing the join of p(x1 y1) and
Q(x2 y2) internally in the ration m : n
This formula can also be derived by drawing perpendiculars from A, P and B on the y axis:
you can also use Heron’s formula to find the area of a triangle.  Equation of a line passing through the point A(x1y1) and B(x2y2)
is
The slope of such line is given as (Y_{2}y_{1}/X_{2}X_{1})
