$A=\left(1,-2\right)$A=\left(1,-2\right)

$B=\left(2,-1\right)$B=\left(2,-1\right)

$\displaystyle C=\left(1, \frac{1}{2} \right)$\displaystyle C=\left(1, \frac{1}{2} \right)

$D=\left(4,4\right)$D=\left(4,4\right)