230

b)
$\overline{OA}=-2\overline{\text{i}}+\overline{\text{j}}$
$\overline{AB}=3\overline{\text{i}}-\overline{\text{j}}$
$\overline{OB}=\overline{OA}+\overline{AB}=3\overline{\text{i}}-2\overline{\text{i}}+\overline{\text{j}}-\overline{\text{j}}=\overline{\text{i}}$

$B=\left(1{,}\ 0\right)$

$\overline{AD}=2\overline{\text{i}}+2\overline{\text{j}}$
$\overline{OD}=\overline{OA}+\overline{AD}=-2\overline{\text{i}}+2\overline{\text{i}}+\overline{\text{j}}+2\overline{\text{j}}=3\overline{\text{j}}$
$D=\left(0{,}\ 3\right)$
$\overline{OC}=\overline{OA}+\overline{AB}+\overline{AD}=-2\overline{\text{i}}+3\overline{\text{i}}+2\overline{\text{i}}+\overline{\text{j}}-\overline{\text{j}}+2\overline{\text{j}}=3\overline{\text{i}}+2\overline{\text{j}}$
$C=\left(3{,}\ 2\right)$