Inputting this function of x into the nth Chebyshev polynomial of the first kind (10[1])yields this function of nx. (10[1])This function equals the average of e to the ix and e to the minus ix, and the hyperbolic form of this function is the average of e (-5[1])to the x and e to the minus x. The first (-5[1])two terms of this function’s Taylor (-5[1])series are one and minus (10[1])one-half x-squared. (10[1])For a complex number of modulus one, this function of the argument is the number’s real part. Pythagoras’ theorem is a special case of a law named after this function. The reciprocal of this function is secant. For 10 points, (10[1])name this trigonometric function that equals adjacent over hypotenuse in a right triangle. ■END■ (10[1])