13. Suppose \( W=\left\{(x, y) \subset R^{2}: x \mid y=0\right\} \). Find the shortest distanee of \( (a, b) \subset R^{2} \) Irom \( W \) with resquet to i) the standard inner product, ii) the inner product defined by \( \left(\left(x_{1}, y_{1}\right),\left(x_{2}, y_{2}\right)\right)=2 x_{1} x_{2}+y_{1} y_{2} \).