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

In triangles $ABC$ and $DEF$,$\angle A = \angle D$,$\angle B = \angle E$ and $AB = EF$. Will the two triangles be congruent? Give reasons for your answer.

$\angle ABD$ and $\angle ACE$ are exterior angles of $\Delta ABC$. If $\angle ABD = 110^{\circ}$ and $\angle ACE = 150^{\circ}$,then $\angle A$ is: (in $^{\circ}$)

$ABC$ is an isosceles triangle in which $AC = BC$. $AD$ and $BE$ are respectively two altitudes to sides $BC$ and $AC$. Prove that $AE = BD$.

In $\Delta ABC$,$AD$,$BE$,and $CF$ are its medians. Prove that $AB + BC + CA > AD + BE + CF$.

In $\triangle PQR,$ if $\angle R > \angle Q,$ then