Chebyshev polynomials

In mathematics the Chebyshev polynomials, named after Pafnuty Chebyshev, are a sequence of orthogonal polynomials which are related to de Moivre's formula and which can be defined recursively. One usually distinguishes between Chebyshev polynomials of the first kind which are denoted and Chebyshev polynomials of the second kind which are denoted. The letter is used because of the alternative transliterations of the name Chebyshev as Tchebycheff, Tchebyshev or Tschebyschow.