Consider the straight line and be the inclination of the straight line as shown in the given diagram now the slope of the represented by . Let be any point on the given line . Let be the X-intercept of the straight line, so the line must passes through the point .
Take as X-intercept of the straight line so the line must passes through the point , i.e. X-intercept. From point draw perpendicular on -axis.
Now from the given diagram, consider the triangle , i.e. , by the definition of slope we take
Now by definition we can use instead of , we get
Which is the equation of straight line having slope and X-intercept .
NOTE: It may be noted that if the line passes through the origin , then take X-intercept is equal to zero i.e. , so the equation of straight line becomes .
Example: Find the equation of straight line having slope and X-intercept is equal to.
Here we have slope and X-intercept
Now using the formula of straight line having slope and X-intercept
Substitute the above values in the formula to get the equation of straight line
Which is the required equation of straight line.