Which of the following is true in a triangle ABC :

$(b+c)\sin\frac{B-C}{2}=2a\cos\frac{A}{2}$ $(b+c)\cos\frac{A}{2}=2a\sin\frac{B-C}{2}$ $(b-c)\cos\frac{A}{2}=a\sin\frac{B-C}{2}$ $(b-c)\sin\frac{B-C}{2}=2a\cos\frac{A}{2}$

$(b-c)\cos\frac{A}{2}=a\sin\frac{B-C}{2}$

Check the option Let the Δ be equilateral ⇒ A = B = C ⇒ (A) (B) and (D) cannot possible.