If a,b,c,d are continued proportion : Prove that : $\displaystyle (\frac{a-b}{c}+\frac{a-c}{b})^2-(\frac{d-b}{c}+\frac{d-c}{b})^2=(a-d)^(\frac{1}{c^2}-\frac{1}{b^2})^2$

After solving LH.S I got : $\displaystyle \frac{2(a-d)}{(bc)^2}$

But after solving R.H.S I am getting $\displaystyle \frac{(a-d)^2(b^2-c^2)}{(bc)^2}$

Please help further..