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(x+3)²=a
a²+3a-4=0
a1+a2=-3 U a1*a2=-4
a1=-4⇒(x+3)²=-4 нет решения
a2=1⇒(x+3)²=1
x+3=-1 U x+3=1
x=-4 U x=-2
-4*(-2)=8
Ответ 8
Sin x * sin y = 1/2 (cos (x-y) - cos(x+y))
cos (x-y) - cos(x+y) = sqrt(3)/2
cosx * cosy = 1/2 (cos (x-y) + cos(x+y))
cos (x-y) + cos(x+y) = sqrt(3)/2
2 * cos(x-y) = sqrt(3)
cos(x-y) = sqrt(3)/2
x-y = +- (pi/6) + 2pi * k
справишься дальше?