The sum of any two sides of a triangle is $\ldots \ldots \ldots$ than the third side.

If $\Delta ABC \cong \Delta DEF$,and the area of $\Delta ABC$ is $58 \ cm^2$,then find the area of $\Delta DEF$ in $cm^2$.

$O$ is a point in the interior of a square $ABCD$ such that $\triangle OAB$ is an equilateral triangle. Show that $\triangle OCD$ is an isosceles triangle.

$CDE$ is an equilateral triangle formed on side $CD$ of a square $ABCD$ (see figure). Show that $\triangle ADE \cong \triangle BCE$.

In quadrilateral $PQRS$,$PQ = PS$ and $QR = RS$. Prove that diagonal $PR$ bisects $\angle QPS$ as well as $\angle QRS$.

$Q$ is a point on the side $SR$ of a $\triangle PSR$ such that $PQ = PR$. Prove that $PS > PQ$.