Д)sin²acos²b-cos²asin²b=(sinacosb-cosasinb)(sinacosb+cosasinb)=sin(a-b)sin(a+b)=
=1/2(cos2b-cos2a)=1/2(1-2sin²b-1+2sin²a)=sin²a-sin²b
sin²a-sin²b=sin²a-sin²b
e)cos²acos²b-sin²asin²b=(cosacosb-sinasinb)(cosacosb+sinasinb)=cos(a+b)cos(a-b)=
=1/2(cos2b+cos2a)=1/2*(1-2sin²b+2cos²a-1)=cos²a-sin²b
cos²a-sin²b=cos²a-sin²b