two-point straight line (slope distance equation) calculator

X1 =
Y1 =
X2 =
Y2 =
 
slope:
distance:
angle:
equation:

it is known that the coordinates of point a are (x1, y1) and the coordinates of point b are (x2, y2). find the equation of the straight line.

(Y-Y1)/(Y2-Y1)=(X-X1)/(X2-X1)