1) 1) sin150=1/2 cos315=√2/2
2) cos300=1/2 sin240=-√3/2
3)tg135=-1 tg210=1/√3
2)sina=√(1-cos²a)=>sina=12/13 cos2a=cos²a-sin²a=25/169-144/169=-119/169
cosa=-√(88)/13 sin2a=2sinacosa=2*9/13*(-√(88)/13)=-36√(22)/169
3)sinacosb-cosasinb+cosasib=(sinacosb)tga=(sin²acosb)/cosa
(-cosacosb)ctgb=(-cosacos²b)/sinb
формулы: sin(a+b)=sinacosb=cosasinb
sin(a-b)=sinacosb-cosbsina
cos(a+b)=cosacosb-sinbsina
cos(a-b)=cosacosb=sinasinb