1)
а)6 - sin2π - 3cosπ + 2sin(π/2)*cosπ =6 -0 -3(-1) +2*1*(-1) = 7 ;
б) sin225° - cos315° = sin(180°+45°) - cos(360° -45°) =
= -sin45° - cos45° = -√2/2 - √2/2 = -√2
2)
а)(1-2cos²x)/(2sin²x-1) = (-cos2x)/(-cos2x)=1
б) sin210°sin150° + cos210°cos150° +tq240°tq210° =
=sin(180°+30°)sin(180° - 30°) +cos(180°+30°)cos(180° - 30°)+ +tq(180°+60°)tq(180°+30°) =- sin30°sin30° -cos30°(-cos30°) +tq60°¹tq30°=
= -1/4 +3/4 +√3*1/√3 =1,5
или короче
sin210°sin150° + cos210°cos150° +tq240°tq210° =
= cos(210° -150°) +tq(180°+60)°*tq(270° -60°)=
=cos60°+tq60°ctq60°=1,5