## Elementary Geometry for College Students (5th Edition)

(-a,-b) and (a,b) Using theorem 10.1.2 Midpoint formula M = ($x_{m}, y_{m})$ = ($\frac{x1+x2}{2}$, $\frac{y1+y2}{2}$) M = ($\frac{-a+a}{2}$, $\frac{-b+b}{2}$) = (0,0)