1)sin5x cos3 x+cos5x sin3x = sin8x
sin(5x+3x)=sin8x
sin8x=sin8x
2)cos5x cos3x - sin5x sin3x = cos8x
cos(5x+3x)=cos8x
cos8x=cos8x
формула *cosA*cosB-sinA*sinB=cos(A+B)
cos55°*cos95°-sin55°*sin95°=cos(55°+95°)=cos150°=cos(180°-30°)=
=-cos30°=-V3/2
Хв квадрате-4-Хв квадрате-5Х=-5Х-4