Question

Докажите тождество sin(π/4+α)=cos(π/4-α)

Answer 1

$sin \beta =cos(\frac{\pi}{2}- \beta )\; \; \to \; \; \beta =\frac{\pi}{4}+ \alpha \\\\sin(\frac{\pi}{4}+ \alpha )=cos(\frac{\pi}{2}-(\frac{\pi}{4}+ \alpha ))=cos(\frac{\pi}{4}- \alpha )$