. Straight Line Any first degree equation in two variables x and y of the form ax by = … ( ) where a , b , c are real numbers and at least one of a , b is non-zero is called “Straight line” in XY plane. . .
Equation of coordinate axes The X axis and Y axis together are called coordinate axes. The x coordinate of every point on OY ( Y axis) is . Therefore equation of OY ( Y axis) is x = (fig . ) The y coordinate of every point on OX ( X axis) is .
Therefore the equation of OX ( X axis) is y = (fig . ) . . Equation of a straight line parallel to X axis Let AB be a straight line parallel to X axis , which is at a distance ‘ b ’.
Then y coordinate of every point on ‘ AB ’ is ‘ b ’. (fig . ) Therefore, the equation of AB is y = b