Respuesta :

(4,5)(2,1)
slope = (1 - 5) / (2 - 4) = -4/-2 = 2

(-2,3)(-4,4)
slope = (4 - 3) / (-4 - (-2) = 1/(-4 + 2) = -1/2

2 and -1/2 are negative reciprocals of each other....therefore, ur lines are perpendicular <==