<span>x²+cx+25=0
</span><span>
</span>D=c²-100<0
c²<100
c₁<10 c₂>-10
c∈(-10;10)
<span />
1)cos 135°=cos(180-45)=-cos45=-√2/2
2) sin 8π/3=sin(3π-π/3)=sinπ/3=√3/2
3) tg 7π/3=tg(2π+π/3)=tgπ/3=√3
4) cos²π/8-sin²π8=cosπ/4=√2/2
Решение на фотографии............