Inputting this function of x into the nth Chebyshev polynomial of the first kind (10[1])yields this function of nx. (10[2])This function (10[1])equals the average (10[1])of e to the ix and e to the minus ix, (10[4])and (10[1]-5[1])the hyperbolic (10[1]-5[1])form (-5[1])of this function (10[2]-5[1])is the average (10[3])of e (-5[1])to the (10[1])x (-5[1])and e to the minus (-5[1])x. (10[1]-5[1])The first (-5[1])two (10[1]-5[1])terms (10[1])of this function’s Taylor (-5[1])series (10[1]-5[1])are (10[1])one (10[1]-5[2])and minus (10[3])one-half (10[1])x-squared. (10[4])For a complex number of (10[1])modulus (-5[1])one, (10[1]-5[1])this function of the argument is the number’s real part. (10[4]-5[1])Pythagoras’ (-5[1])theorem is a special case of a law named after (10[1])this (10[1])function. (10[3]-5[2])The reciprocal (10[1])of this function (10[3])is (10[2])secant. (10[3])For 10 points, (10[1])name this trigonometric (10[1])function (10[2])that (10[1])equals adjacent (10[1])over hypotenuse (10[1])in a right triangle. (10[2])■END■ (10[7])