# Triangle of given area

Geometry Level 3

Let $$PQR$$ be a triangle of area $$\Delta$$ with $$a = 2, b = \frac{7}{2}$$ and $$c = \frac{5}{2}$$, where $$a, b$$ and $$c$$ are the lengths of the sides of the triangle opposite to the angles at $$P, Q$$ and $$R$$ respectively. Then $$\frac{ 2 sin P - sin 2 P}{ 2 sin P + sin 2 P}$$ equals

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