Question

Помогите с решением, пожалуйста

Answer 1

1/2 ×(сos(п/6+2t)+cos(п/3))-1/2 ×(cos(-п/6-2t)+cos(2п/3))=1/2 ×(сos(п/6+2t)+1/2)-1/2 ×(cos(п/6+2t)-1/2)=1/2 ×сos(п/6+2t) +1/4 -1/2 ×cos(п/6+2t) +1/4=1/2

Answer 2

cos(π/4-t)=cos(π/2-(π/4+t))=sin(π/4+t)
cos(5π/12+t)=cos(π/2-(π/12-t))=sin(π/12-t)
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cos(π/4+t)cos(π/12-t)-sin(π/4+t)sin(π/12-t)=cos(π/4+t+π/12-t)=
=cosπ/3=1/2