*Slope of a straight line

• Slope (symbol, m) of a straight line is defined as the tan of the anticlock wise angle made by that line with the positive horizontal axis.
• i.e. m = tan θ             
• As tan θ can have any real value, so we can say
• 
• Slope of a straight line passing through points A (x₁, y₁) & B (x₂, y₂) is given by
• 
• Here Δx, Δy represents change in x & y coordinates respectively.
• If two lines are ||, then their slopes are equal.
• If two lines are perpendicular then the product of their slope is – 1.