Exercise 11 Page 160

Parallel lines have the same slope but different $y\text{-}$intercepts. Perpendicular lines have slopes that are opposite reciprocals of one another. Therefore, to determine if the lines are parallel, perpendicular, or neither, we first need to find their slopes using the Slope Formula.

Line	Points	$\frac{y_2-y_1}{x_2-x_1}$	$m$	Simplest form
$1$	$(\text{-}9,3)\&(\text{-}5,7)$	$\frac{7-3}{\text{-}5-(\text{-}9)}$	$\frac{4}{4}$	$1$
$2$	$(\text{-}11,6)\&(\text{-}7,2)$	$\frac{2-6}{\text{-}7-(\text{-}11)}$	$\frac{\text{-}4}{4}$	$\text{-}1$

These lines have different slopes so they cannot be parallel. We can determine if they are perpendicular by multiplying the slopes. Since the product of the slopes equals $\text{-}1,$ they are perpendicular.