Important formula of Equation of a line

Important formula of Equation of a line

• If two points are given, then Slope (m) = (y2-y1)/(x2-x1)
• If a point , and slope are given , then Slope (m)= (y-y1)/(x-x1)
• If two lines are ‘Parallel’ to each other then their slopes are equal i.e m1=m2.
• If two lines are ‘Perpendicular’ to each other then product of their slopes is -1 i.e m1 *m2 = -1
• Depending upon the question You may have to use equation of straight line as

a)      Y=mx + c, where ‘c’ is the y- intercept. OR    b) (y-y1)= m.( x-x1)