- Найдите числовое значение выражения:
1) (sin315 – соѕ315');
2) (sin225° - cos225°);
3) (sin135° + cos135');
4) (sin315" + cos315)2.

1) (sin315 – соѕ315')=sin(270+45)-cos(270+45)=-cos45-sin45=

=-sqrt(2)/2-sqrt(2)/2=-sqrt(2);

2) (sin225° - cos225°)=sin(180+45)-cos(180+45)=-sin45+cos45=

=-sqrt(2)/2+sqrt(2)/2=0;

3) (sin135° + cos135')=sin(90+45)+cos(90+45)=cos45-sin45

=sqrt(2)/2-sqrt(2)/2=0;

4) (sin315" + cos315)^2=1+sin630=1+sin(720-90)=1+sin(-90)=1-1=0