Question

29 номер пожалуйста

Answer 1

$f(x) = cosx\\a) f(47\pi) = cos(47\pi) = cos(46\pi + \pi) = cos(2*23\pi + \pi) = cos\pi = -1\\b) f(-\frac{37\pi}6) = cos(-\frac{37\pi}6) = cos(-\frac{36\pi}6 - \frac\pi6) = cos(-6\pi-\frac\pi6) = cos(-\frac\pi6) = \frac{\sqrt3}2\\c) f(-\frac{-9\pi4}) = cos(-\frac{9\pi}4) = cos(-\frac{8\pi}4 - \frac\pi4) = cos(-2\pi - \frac\pi4) = cos(-\frac\pi4) = \frac{\sqrt2}2$