Пожолуста
a) 2+cos^2x=2sinx
b) 3—3cosx =2sin^2x​

b)

3-3cosx=2(< var > 2cos^{2}(x) < /var ><var>2cos

2

(x)</var> -1)

4< var > cos^{2}(x)+3*cos(x)-5=0 < /var ><var>cos

2

(x)+3∗cos(x)−5=0</var> cos(x)=t,-1<t<1

4t^2+3t-5=0

D=9+80=89

< var > \sqrt{D}=89\approx=9.4 < /var ><var>

D

=89≈=9.4</var>

< var > x_1=(-3-9.4)/8=-5/8 < /var ><var>x

1

=(−3−9.4)/8=−5/8</var>

< var > x_2=(-3+9,4)/8=0.8 < /var ><var>x

2

=(−3+9,4)/8=0.8</var>

Обратная замена

cosx=-5/8 cosx=0.8

x=+-arccos(-5/8)+2< var > \pi < /var ><var>π</var> *n x=+-arccos(0.8)+2< var > \pi < /var ><var>π</var> *n