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

来源:学生作业帮助网 编辑:六六作业网 时间:2024/12/28 15:31:10
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