Question

помогите пожалуйста!!!

Answer 1

$f(x)=3cos(x-frac{pi}{4})\\f(-frac{pi}{4})=3cos(-frac{pi}{4})-frac{pi}{4})=3cos(-frac{pi}{2})=3cos, frac{pi}{2}=3cdot 0=0\\f(0)=3cos(0-frac{pi}{4})=3cosfrac{pi}{4}=3cdot frac{sqrt2}{2}=frac{3sqrt2}{2}\\f(pi )=3cos(pi - frac{pi }{4})=-3cosfrac{pi}{4}=-3cdot frac{sqrt2}{2}=- frac{3sqrt2}{2} \\P.S.; ; Formylu; privedeniya:; ; cos(pi -frac{pi}{4})=-cosfrac{pi}{4}=-frac{sqrt2}{2}$