In the given Fig. \(9, A B C D\) is a four-bar mechanism, At the instant shown \(A B\) and \(C D\) are vertical and \(B C\) is horizontal. \(A B\) is shorter than \(C D\) by \(30 \mathrm{~cm}, A B\) is rotating at \(5 \mathrm{rad} / \mathrm{s}\) and \(C D\) is rotating at \(2 \mathrm{rad} / \mathrm{s}\). The length of \(A B\) is

(a) \(10 \mathrm{~cm}\)

(b) \(20 \mathrm{~cm}\)

(c) \(30 \mathrm{~cm}\)

(d) \(50 \mathrm{~cm}\).

B C A TAM D Fig.9