Correct answer is : 3

\(\overrightarrow{\mathrm{R}}=\left(\mathrm{A}+\frac{\mathrm{A}}{\sqrt{2}}\right) \hat{\mathrm{i}}+\left(\mathrm{A}-\frac{\mathrm{A}}{\sqrt{2}}\right) \hat{\mathrm{j}}\)
\(|\vec{R}|=\sqrt{\left(A+\frac{A}{\sqrt{2}}\right)^{2}+\left(A-\frac{A}{\sqrt{2}}\right)^{2}}=\sqrt{3} \mathrm{A}\)