Question

Упростите:
√2/2* sina - cos(п/4 - а)

Answer 1

$\displaystyle\bf\\\frac{\sqrt{2} }{2} \cdot Sin\alpha -Cos\Big(\frac{\pi }{4} -\alpha \Big)=Sin\frac{\pi }{4}\cdot Sin\alpha -\Big(Cos\frac{\pi }{4} Cos\alpha +Sin\frac{\pi }{4} Sin\alpha \Big)=\\\\\\=Sin\frac{\pi }{4}\cdot Sin\alpha -Cos\frac{\pi }{4} Cos\alpha -Sin\frac{\pi }{4} Sin\alpha=-Cos\frac{\pi }{4} Cos\alpha =-\frac{\sqrt{2} }{2} Cos\alpha$