9cos^2a-6+9sin^2a =9(cos^2a+sin^2a)-6= 9-6=3
X 3 + 6 x 2<span> + 11 x + 6 = 0 </span>
Коэффициенты:
a = 6;
b = 11;
<span>c = 6;
</span><span>Q = <span>( a 2 - 3b )/9</span> = <span>( (6) 2 - 3 × (11))/9</span> = 0.3333
</span><span>R = <span>( 2a 3 - 9ab + 27c )</span> /54 = <span>( 2 × (6) 3 - 9 × (6) × (11) + 27 × (6) )</span><span> /54 = 0
</span></span>т. к. R ^22<span> < Q^ </span>3<span> => по методу Виета-Кардано, уравнение имеет три действительных корня</span>
x 1<span> = -3</span>
x 2<span> = -1</span>
x 3<span> = -2</span>
1.1,2,5
2.угол 2=180-угол 1=180-38=142