Consider a triangle $$ABC$$ and let $$a, b$$ and $$c$$ denote the lengths of the sides opposit 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

Let $$ABC$$ and $$ABC'$$ be two non-congruent triangles with sides $$AB=4$$, $$AC=AC'$$$$=$$$$2\sqrt 2 $$ and angle $$B = {30^ \circ }$$. The absolute value of the difference between the areas of these triangles is