1) cos(123+57)= cos 180= -1
2) sin(π/4+a)-1/(√2•cosa)=sin(π/4)•cosa+cos(π/4)•sina-1/(√2•cosa)==1/(√2)•cosa+1/(√2)•sina-1/(√2)•cosa=1/(√2)•sina.
3)
4) 0,2588190451
1) cos(123+57)= cos 180= -1
2) sin(π/4+a)-1/(√2•cosa)=sin(π/4)•cosa+cos(π/4)•sina-1/(√2•cosa)=
=1/(√2)•cosa+1/(√2)•sina-1/(√2)•cosa=1/(√2)•sina.
3)
4) 0,2588190451