Formula_20180

\[\begin{gathered}\hat{T}_{0}(x)=\frac{1}{\sqrt{\pi}} T_{0}(x)=\frac{1}{\sqrt{\pi}}, \\\hat{T}_{n}(x)=\sqrt{\frac{2}{\pi}} T_{n}(x)=\sqrt{\frac{2}{\pi}} \cos (n \arccos x), \quad n \geqslant 1 .\end{gathered}\]