sin(x-π/4)=√2/2
9-(2s-1)²=
=9-(4s²-4s+1)=
=9-4s²+4s-1=
=-4s²+4s+8=
=4(-s²+s+2)=
=4(s+1)(2-s)
кос105=0.26
кос75=0.26
<span>cos 105-cos75= 0</span>
Ответ: 4.