Straight Lines
1.0 Definition
1.0 Definition
A straight line is defined as the curve which is such that the line segment joining any two points on it lies wholly on it.
The equation of straight line is the relation between $x$ and $y$, which is satisfied by the co-ordinates of each and every point on the same line.
The general equation of straight line is written as $$ax+by+c=0$$
or, $$\left( {\frac{a}{c}} \right)x + \left( {\frac{b}{c}} \right)y + 1 = 0$$
or, $$px + qy + 1 = 0$$ where $p = \frac{a}{c}{\text{ and }}q = \frac{b}{c}$
The above equation proved that the number of arbitrary constants in the equation of straight line is two i.e., $p$ and $q$. Hence to completely determine the equation of a straight line, we require two conditions to find the two unknowns in the equation.
