Замена: x²<span>+x+10 = p
(p+9x)*p = 10x</span>²
p² + (9x)*p - 10x² = 0
D=81x²+40x² = (11x)²
p₁ = (-9x-11x)/2 p₂ = (-9x+11x)/2
x²+x+10 = -10x x²+x+10 = x
x²+11x+10 = 0 x² = -10 нет решений
по т.Виета корни (-1) и (-10)
Sinx/2<_1/2
x/2<_p/6
x/2<_5p/6
x<_p/3+2pn
x<_5p/3+2pn
<span>sin^2 (a+B) - sin^2 (a-B)=sin 2a sin2B</span>