If the angles of a triangle are in the ratio $4: 1: 1$, then the ratio of the longest side to the perimeter is

In $\triangle \mathrm{ABC}$, with usual notations, if $\mathrm{b}=3$, $c=8, \mathrm{~m} \angle \mathrm{~A}=60^{\circ}$, then the circumradius of the triangle is _______ units.

If the lengths of the sides of triangle are 3,5,7, then the largest angle of the triangle is

In $\triangle A B C$, with usual notations, if $\frac{1}{b+c}+\frac{1}{c+a}=\frac{3}{a+b+c}$, then $m \angle C$ is equal to