In a triangle ABC, A=2 pii/3, b-c=3.3^1/2 cm and area of triangle ABC =9.3^1/2/2 cm^2.Then a is(A) 6.3^1/2 cm(B)9 cm(C)18cm(D)none of these

We have an angle A
The difference of 2 sides: b-c which can be used to frame an equality by squaring it
So the formulae that need to be used are:
Area of triangle: ½ bc Sin A
a²= b² + c²-2bcCosA (COsine law of triangle)
a/SinA= b/SinB=c/SinC (Sin law of triangle)

Use these formulae to get the answer...