\[\int_{-1}^{1}\frac{T_{j}\left(x\right)T_{k}\left(x\right)}{\sqrt{1-x^{2}}}\,%
\mathrm{d}x=\begin{cases}\pi,&j=k=0,\\
\frac{1}{2}\pi,&j=k\neq 0,\\
0,&j\neq k,\end{cases}\]