Gradient of PB (m1) = m Gradient of PB’ (m2) = 1 m If the gradients of the two perpendicular lines are m1 and m2, then m1m2 = -1. If two lines are parallel with one another, the gradient of the two lines are the same. m1 m2 m1 = m2 1) Find the equation of the line that is parallel to 6x + 2y = 5 and passing through point (4,8). 2 y 6 x 5 5 y 3 x 2 y 8 3( x 4) y 3 x 4 2) Find the equation of the line that is perpendicular to y = 3x + 5 and passing through point (-2,5). 1 m2 3 1 y 5 ( x 2) 3 3 y 15 x 2 3 y x 13