Btw, how do I find my previous posts on here ?

OK, can someone explain. I know the gradient of a line, and i'm being asked to find theequationof the line perpendicular to it.

The gradient of the line is 1/2. So m1m2 = -1, so m2 = - 2 ?

So how do I find the equation - in the form ax + by + c = 0

The points are A (-1, -2 ) B ( 7 , 2) and C (6, 4)

please help!