A)tg21π/4=tg(5π+π/4)=tgπ/4=1
б)sin11π/6=sin(2π-π/6)=sin(-π/6)=-sinπ/6=-1/2
в)cos(-2π/3)=cos2π/3=cos(π-π/3)=-cosπ/3=-1/2
1) 4 * 6 = 24
24/36 = 4/6=2/3
2) 86 + 1 = 87
3) 810
4) 14 + 18х = -6х +2
24х = -12
х = -0.5
5) также = 20 + 4х - 5
2х +1=20 + 4х - 5
2х = -24
х=-12
6) х= -8
7) 36+4х = х+3
3х=-33
х=-11
sin7*cos23+sin23*cos7=sin(7+23)=sin30=0,5
<span>(0,98 - 0,312 : 0,3) * 25 + 1/9 = </span>(0,98 - 1,04) * 25 + 1/9 = - 0,06 * 25 + 1/9 = - 1,5 + 1/9 = - 3/2 + 1/9 = - 27/18 + 2/18 = - 25/18 = - 1 7/18