## Algebra and Trigonometry 10th Edition

Slope of Line 1 : $m_1=\frac{y_2-y_1}{x_2-x_1}=\frac{-1-9}{0-5}=\frac{-10}{-5}=2$ Slope of Line 1 : $m_2=\frac{y_2-y_1}{x_2-x_1}=\frac{3-1}{0-4}=\frac{2}{-4}=-1/2$ Hence both lines are perpendicular as $m_1 * m_2 = -1$