the equation of a straight line is given by 2x + y = 4 (a) find the vector equation of a unit normal from the origin to the line and (b) the equation of a line passing through P(0,2) and normal to 2x + y = 4. i know i need to use the dot product some how but i am utterly confused as to where to begin! please help. i think first the vector equation for the given line is r = < 1 , -2 > then i need to dot r with rperp and set equal to 0? i am very confused. thanks!