The three angle bisectors of a triangle are concurrent. Their point of concurrence is called the

In $△ABC$, $\mathrm{AB}=$_____$\mathrm{cm}$.

In the given figure, $AD$ is the bisector of $\angle BAC$. If $AB=10cm, AC=6cm$ and $BC=12cm$. Find $BD$.

In the given fig.$AM\perp BC$ and $AN$ is the bisector of $\angle A$. If $\angle B=65°$ and $\angle C=33°$, then the value of $\angle MAN$ will be

In $△PQR$, the bisector of $\angle P$ intersects $QR$ in $M$. If $PQ=10, PR=12, QM=8$ then $QR=$ _____.

Let $a, b, c$ be the side-length of a triangle and $l, m, n$ be the lengths of its medians. Put $K=\frac{l+m+n}{a+b+c}$ Then, as $a, b, c$ vary, $K$ can assume every value in the interval