Precalculus (6th Edition)

See p. 187, Midpoint Formula $M=(\displaystyle \frac{x_{\mathrm{I}}+x_{2}}{2},\frac{y_{1}+y_{2}}{2})$ -------- $(x_{1}, y_{1})=(0,0),\quad (x_{2}, y_{2})=(4,4)$ $M=(\displaystyle \frac{0+4}{2}, \frac{0+4}{2})=(2,2)$ (the midpoint is a point represented as an ordered pair, not a number)