${\\displaystyle T_{n}(x)}$

${\\displaystyle U_{n}(x)}$

The Chebyshev polynomials of the first kind ${\\displaystyle T_{n}}$ are defined by:

${\\displaystyle T_{n}(\\cos \ heta )=\\cos(n\ heta ).}$

Similarly, the Chebyshev polynomials of the second kind ${\\displaystyle U_{n}}$ are defined by:

${\\displaystyle U_{n}(\\cos \ heta )\\sin \ heta =\\sin {\ig (}(n+1)\ heta {\ig )}.}$