The length of the belt in the case of a cross-belt drive is given in terms of centre distance between pulleys \((C)\), diameters of the pulleys \(D\) and \(\mathrm{d}\) as

(a) \(2 C+\frac{\pi}{2}(D+d)+\frac{(D+d)^{2}}{4 C}\)

(b) \(2 C+\frac{\pi}{2}(D-d)+\frac{(D+d)^{2}}{4 C}\)

(c) \(2 C+\frac{\pi}{2}(D+d)+\frac{(D-d)^{2}}{4 C}\)

(d) \(2 \mathrm{C}+\frac{\pi}{2}(\mathrm{D}-d)+\frac{(\mathrm{D}-d)^{2}}{4 \mathrm{C}}\)