求sin(-1320)cos1110+cos(-1020)sin750的值

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求sin(-1320)cos1110+cos(-1020)sin750的值
求sin(-1320)cos1110+cos(-1020)sin750的值

求sin(-1320)cos1110+cos(-1020)sin750的值
1

sin(-1320)cos1110+cos(-1020)sin750
=sin(1440-1320)cos(960+150)+cos(-960-60)sin(720+30)
=sin120°cos150°+cos60°sin30°
=√3/2*(-√3)/2+1/4
=-3/4+1/4
=-1/2

sin(-1320)cos1110+cos(-1020)sin750=sin120cos30+cos60sin30=3/4+1/4=1