sin^2a+cos^2=1
sin^2a+(-корень10/10)^2=1
sin^2a+10/100=1
sin^2a=1-1/10=9/10
sin^2=0.9
sina=3/корень10
tg=sin/cos
tg= (3/корень10)/(-корень10/10)= -30/100=-0.3
<span>4/9*(9/2y-3/2)-2/7*(7/6-7/2y)=4/9*9/2у-4/9*3/2-2/7*7/6+2/7*7/2у=2у-2/3-1/3+у=3у-1</span>