Mathematics - Properties of Triangles Question with Solution | TestHub

Consider a triangle $ABC$ and let $a,b$ and $c$ denote the lengths of the sides opposite to vertices $A,B$ and $C$ respectively. Suppose $a=6,b=10$ and the area of the triangle is $15\sqrt{3}$. If $\angle ACB$ is obtuse and if $r$ denotes the radius of the incircle of the triangle, then $r^2$ is equal to