A) $A{B}^2=A{C}^2+B{C}^2+2AB.BC$ B) $A{C}^2=A{B}^2+B{C}^2-2AB.BC$ C) $A{B}^2+B{C}^2=2(A{D}^2+B{D}^2)$ D) $A{B}^2+A{C}^2=2(A{D}^2+B{D}^2)$