Equations of a Straight Line

🔹 Equation of x-axis is y = 0 and that of y-axis is x = 0

🔹 Equation of a line parallel to x-axis is y = b where b is the distance of the line from the x-axis.

🔹 Equation of a line perpendicular to y-axis is x = a where a is the distance of the line from the y-axis.

🔹 Equation of a line whose slope is m and which cuts off an intercept c from the y-axis is y = mx + c

🔹 In particular, equation of a line whose slope is m and which passes through the origin is y = mx

🔹 The equation of a line whose slope is m and which passes through the point (x₁, y₁) is (y-y₁)=m(x-x₁).

🔹 The equation of a line passing through two points (x₁, y₁) and (x₂, y₂).