$\begin{array}{1 1}(a)\;\large\frac{2b}{c+a},\frac{c-a}{c+a}&(b)\;\large\frac{c+a}{2b},\frac{c-a}{c+a}\\(c)\;\large\frac{2b}{c-a},\frac{c-a}{c+a}&(d)\;\large\frac{2b}{c+a},\frac{c+a}{c-a}\end{array}$