the argument, \(\theta\) of cos or sin should be dimensionless.
therefore,
dimension of \(\mathrm{Bx}=[M L T]\)
\([B]\left[L^{\prime}\right]=[M L T]\)
\([B]=\left[M L^{0} T\right]\)
Similarly \([D]\left[T^{\prime}\right]=[M L T]\)
\([D]=\left[M L T^{0}\right.\)
dimension of \(D/B=\frac{\left[M L T^{0}\right]}{\left[M L^{0} T\right]}\)
\(=\left[L^{1} T^{-1}\right]\)