## Elementary Geometry for College Students (6th Edition)

We use the equation for slope: $m = \frac{y_2-y_1}{x_2-x_1}$ We find: $m_1 = \frac{-3-(-11)}{-5-1}=\frac{-4}{3}$ $m_2 = \frac{-11-(-6)}{1-7}=\frac{5}{6}$ $m_3 = \frac{-6-2}{7-1}=\frac{-4}{3}$ $m_4 = \frac{-3-2}{-5-1}=\frac{5}{6}$ Since two sets of sides have equal slopes, the shape is a parallelogram.