NIMCET 2015 Question Paper with solutions

We have, $\left(-4,5\right)$ is one vertex of the square and equation of diagonal is $7\mathit{x}-\mathit{y}+8$. Diagonals of square are perpendicular to each other
∴ Equation of other diagonal which is perpendicular to
$7\mathit{x}-\mathit{y}+8=0$ is
$\mathit{x}+7\mathit{y}=\mathit{\lambda }$
It passes through $\left(-4,5\right)$
∴ $-4+35=\mathit{\lambda }\Rightarrow \mathit{\lambda }=31$
Hence, equation of diagonal is, $\mathit{x}+7\mathit{y}=31$