42-6×7/37-11=42-42/26=0/26=0
X^2>-16 x∈∅
x^2<1
X1<1
X2>-1
X∈(-1;1)
формула *cosA*cosB-sinA*sinB=cos(A+B)
cos55°*cos95°-sin55°*sin95°=cos(55°+95°)=cos150°=cos(180°-30°)=
=-cos30°=-V3/2
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