Elementary Geometry for College Students (6th Edition)

Given Points(a,0) and (0,a) if x1=a,y1=0,x2=0,y2=a Slope of the line segment is$\frac{y2-y1}{x2-x1}$ $\frac{a-0}{0-a}$ = $\frac{-a}{a}$ =-1