пожалуйста помогите решить: 1. (sin 75 - cos 75) / (cos15 + sin 15) =
2. cos 20*cos 25 - cos 70*sin 25=

(Sin 75-cos 75)/(cos15+sin15)=(sin(90-15)-cos(90-15))/
(Cos 15+sin 15)=(cos 15-sin 15)/(cos 15+sin 15)=
(cos 15-sin 15)•(cos 15+sin 15)/(cos 15+sin 15)/(cos 15+sin 15)=(cos^2(15)-sin^2(15))/(cos^2(15)+2sin15cos15+cos^2(15))=cos30/(1+sin30)=
(V3)/2:(1+1/2)=(V3)/2:(3/2)=(V3)/2•2/3=(V3)/3
2)cos 20•cos 25-cos 70•sin 25=cos 20•cos 25-cos (90-20)sin 25=cos 20•cos 25-sin20•sin 25=cos(20+25)=cos45=(V2)/2