1)cos(a+b)+2sinasinb/2sinacosb-sin(a+b)=(cosacosb-sinasinb+2sinasinb)/(2sinacosb-sinacosb-cosasinb)==(cosacosb+sinasinb)/(sinacosb-cosasinb)=cos(a-b)/sin(a-b)=ctg(a-b)2)(sina/sin2a-cosa/cos2a)*cosa-cos7a/sina=(sinacos2a-cosasin2a)/sin2acos2a* (-2sin3asin4a)/sina==2sin(a-2a)/sin4a* (-2sin3asin4a)/sina=-2sina*(-2sin3a)/sina=4sin3a3)sin(a+b)+sin(a-b)/sin(a+b)-sin(a-b)==(sinacosb+cosasinb+sinacosb-cosasinb)/(sinacosb+cosasinb-sinacosb++cosasinb)=2sinacosb/2cosasinb=tga*ctgb4)(sina-cosa)2-1+sin4a/cos2a+cos4a==(sin²a-2sinacosa+cos²a-sin²a-cos²a+sin4a)/2cos3acosa==(sin4a-sin2a)/2cos3acosa=2sinacos3a/2cos3acosa=sina/cosa=tga