...........................
14y + 12y - 2y^2 = 26y - 2y^2
<span>sin^2 a * tg a - cos^2 a=</span>
<span>= sin^3 a / cos a - 1+ sin^2 a =</span>
<span>= sin^3 a / sqrt(1-sin^2 a) - 1+ sin^2 a =</span>
<span>= 1/27 / sqrt(1-1/9) -1 + 1/9 = </span>
<span>= 1/(9sqrt(8) -8/9 = </span>
<span>= (sqrt(2)-32)/36</span>
.....................................................