Let PQR be a triangle of area $$\triangle$$ 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 $$\frac{2 \sin P - \sin 2P}{2 \sin P + \sin 2P}$$ equals

A

$$\frac{3}{4 \triangle}$$

B

$$\frac{45}{4 \triangle}$$

C

$$\left(\frac{3}{4 \triangle}\right)^2$$

D

$$\left(\frac{45}{4 \triangle}\right)^2$$