If $a,b,c$ be the sides of a triangle ABC and if roots of the equation . $a(b-c)x^2+b(c-a)x+c(a-b)=0$ are equal , then $\sin ^2 \bigg(\large\frac{A}{2} \bigg) ,$$ \sin ^2 \bigg(\large\frac{B}{c} \bigg),$$ \sin ^2 \bigg(\large\frac{c}{2} \bigg) $are in

Question

$\begin{array}{1 1} A.P \\ G.P \\ H.P \\ A.G.P \end{array} $