sin(x+1080°)cos(x-360°)=2a+1.求实数a的取值范围

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sin(x+1080°)cos(x-360°)=2a+1.求实数a的取值范围sin(x+1080°)cos(x-360°)=2a+1.求实数a的取值范围sin(x+1080°)cos(x-360°)=

sin(x+1080°)cos(x-360°)=2a+1.求实数a的取值范围
sin(x+1080°)cos(x-360°)=2a+1.求实数a的取值范围

sin(x+1080°)cos(x-360°)=2a+1.求实数a的取值范围
sin(x+1080°)cos(x-360°)=sinxcosx=0.5sin2x=2a+1
-0.5≤2a+1≤0.5
-3/4≤a≤-1/4

-3/4

因为sin(x+1080°)cos(x-360°)=sinxcosx=0.5sin(2x)=2a+1,所以sin(2x)=4a+2
因为-1<=sin(2x)<=1,所以-1<=4a+2<=1.
所以-0.75<=a<=-0.25