1
tg23*tg(270+23)+sin52*sin(180-52)-sin(270+52)*sin(90+52)=
=tg23*(-ctg23)+sin52*sin52+cos52*cos52=-1+sin²52+cos²52=-1+1=0
2
<span>(1-2sin²13°) × cos64° / (2cos²19° - 1)=cos26*sin26/cos38=
=(sin52)/2cos(90-52)=(sin52)/2sin52=1/2</span>
15 дели на 3 = 5
и 5 умножь на 8 = 40
12/(у-3) +(3-у)/3=(у-9)/(3-у)
12/(у-3)+(3-у)/3= -(у-9)/(у-3) у≠3
12*3+(3-у)(у-3)= -3(у-9)
36 - (3-у)(3-у)= - 3у+27
36-9+6у-у²+3у-27=0
-у² +9у =0
у² -9у=0
у(у-9)=0
у1=0
у=9=0
у2=9
3x-6-3=10. 3=0 или x-6=0. x=6