Given a function $f$ in the class $\operatorname{Lip}(\alpha,p)$ ($0<\alpha\leq1,p\geq1$), Mittal and Singh (2014) approximated such an $f$ by using trigonometric polynomials, which are the $n^{th}$ terms of either certain Riesz mean or Nörlund mean transforms of the Fourier series representation for $f$. They showed that the degree of approximation is $O((\lambda(n))^{-\alpha})$ and extended two theorems of Leindler (2005) where he has weakened the conditions on $\{p_n\}$ given by Chandra (2002) 13--26], to more general classes of triangular matrix methods. We obtain the same degree of approximation for a more general class of lower triangular matrices.