已知sin(x+π/6)=1/4,求sin(7π/6+x)+cos(5π/6-x)平方的值已知sin(x+π/6)=1/4,求sin(7/6π+x)+cos(5/6π-x)平方的值
问题描述：
已知sin(x+π/6)=1/4,求sin(7π/6+x)+cos(5π/6-x)平方的值
已知sin(x+π/6)=1/4,求sin(7/6π+x)+cos(5/6π-x)平方的值
答
shi 5
答
因为sin(x+π/6)=1/4,所以sin(7π/6+x)=sin(π+π/6+x)=-sin(x+π/6)=-1/4,cos^(5π/6-x)=cos^(π-(π/6+x))=cos^(x+π/6)=1-sin^(x+π/6)=1-/16=15/16.sin(7π/6+x)+cos^2(5π/6-x)=-1/4+15/16=11/16