The sum of the three angles of a triangle is $\ldots \ldots \ldots$ (in $^o$)

Prove that the medians of an equilateral triangle are equal.

In $\Delta PQR$,$PQ = PR$. If $\angle Q = 48^{\circ}$,then find $\angle P$ and $\angle R$.

How many triangles can be drawn having its angles as $45^{\circ}, 64^{\circ}$ and $72^{\circ}$? Give reason for your answer.

$S$ is any point in the interior of $\triangle PQR$. Show that $SQ + SR < PQ + PR$.

In $\Delta ABC$,$\angle B = \frac{\angle A + \angle C}{2}$ and $\angle A : \angle C = 1 : 2$. Find the measure of each angle of $\Delta ABC$.