The coordinates of the vertices of triangle LMN are L(-3, 4) M(-2, 0) and N(6, 2) Is triangle LMN a right triangle?

Prove your answer without graphing. You can use a graph to help you, but you must prove it using slope
(Hint: RT Tri. have one 90 degrees angle with perpendicular lines - slopes of those lines are opposite reciprocal)