In $\Delta XYZ$,$m \angle Y = 90^\circ$ and $\overline{YM}$ is an altitude to the hypotenuse $\overline{XZ}$. If $XM = 5$ and $ZM = 4$,find $YZ$.

$\Delta ABC \sim \Delta PQR$ for the correspondence $ABC \leftrightarrow RPQ$. If $m \angle A + m \angle C = m \angle B$,then in $\Delta PQR$,$\ldots \ldots \ldots$ is a right angle.

In $\Delta ABC$,$m \angle B = 90^{\circ}$ and $AC = 14\sqrt{2}$. If $AB = BC$,find the area of $\Delta ABC$.

Below are given the measures of sides $\overline{PQ}$,$\overline{QR}$ and $\overline{PR}$ of $\Delta PQR$. In each case,determine whether $\Delta PQR$ is a right-angled triangle or not. If it is a right-angled triangle,state which angle is a right angle: $PQ = 15, QR = 17, PR = 8$.

In $\Delta ABC$,$m\angle B = 90^{\circ}$. $D$ is the midpoint of $\overline{BC}$ and $F$ is the midpoint of $\overline{AB}$. Prove that $AD^{2} + CF^{2} = \frac{5}{4} AC^{2}$.

In $\Delta XYZ,$ the bisector of $\angle X$ intersects $\overline{YZ}$ at $T$. If $XY = 10, XZ = 14$ and $YT = 5,$ find $YZ.$