find the gradient of a line pe

rpendicular to the line joining these pairs of points
(a) (1,2) and (5,-6)
(b) (2,4) and (3,8)
(c) (-2,1) and (2,-4)

perpendicular lines have slopes which are negative reciprocals. So,

(a) slope = (-6-2)/(5-1) = -2 so ⊥ slope is 1/2
do the others in like wise