a) sin 13п/6 =sin(12π/6+π/6)=sin(2π+π/6)=sin π/6=1/2=0.5
б) tg (-11п/6) =-tg(11π/6)=-tg(12π/6-π/6)=-tg(2π-π/6)=tgπ/6=√3/3
в)cos п + ctg 4п/3 =-1+√3/3
г)tg п/4 ctg (-п/4) + cos 3п/2 sin п/2 =-tg π/4*ctg π/4+0*1=-1
д) sin 405º + cos 225º tg225º = sin(360°+45°)+cos(180°+45°)*tg(180°+45°) =sin45°+(-cos45°)*tg45°=√2/2-√2/2*1=0
D=25+24=49
x1=(5+7)/-4=-3
x2=(5-7)/-4=1/2
____-3____1/2___》
- + -
х €(-беск;-3]U [1/2;+беск)
2) D=1+48=49
x1=(1+7)/-4=-2
x2=(1-7)/-4=1.5
____-2___1.5___》
- + -
x €[-2,1.5]