# Calculating values of trig functions

by Felix83
Tags: functions, trig, values
 P: 367 Calculators use partial sums of power series to approximate sine and cosine. The power series for sine is: $$sin(x) = x - \frac{1}{3!} * x^{3} + \frac{1}{5!} * x^{5} - \frac{1}{7!} * x^{7} + ...$$ Cosine: $$cos(x) = 1 - \frac{1}{2!} * x^{2} + \frac{1}{4!} * x^{4} - \frac{1}{6!} * x^{6} + ...$$ I'm not sure how many terms they usually use, but that doesn't really matter. The more terms, the more accurate.