## Geometry: Common Core (15th Edition)

We know that if the slopes of two lines are the same, then they are parallel. To check whether the slopes are the same, we use the equation for slope: $$\frac{y_2-y_1}{x_2-x_1}$$ $$\frac{3-1}{1+5}= 1/3$$ $$\frac{2+2}{4+4}=1/2$$