已知sin(x+π/6)的 =1/4,求sin(7π/6 +x)+cos(5π/6 -x)的平方的值答案是11/16

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已知sin(x+π/6)的=1/4,求sin(7π/6+x)+cos(5π/6-x)的平方的值答案是11/16已知sin(x+π/6)的=1/4,求sin(7π/6+x)+cos(5π/6-x)的平方

已知sin(x+π/6)的 =1/4,求sin(7π/6 +x)+cos(5π/6 -x)的平方的值答案是11/16
已知sin(x+π/6)的 =1/4,求sin(7π/6 +x)+cos(5π/6 -x)的平方的值
答案是11/16

已知sin(x+π/6)的 =1/4,求sin(7π/6 +x)+cos(5π/6 -x)的平方的值答案是11/16
sin(x+π/6)的 =1/4
sin(7π/6 +x)+ [cos(5π/6 -x)]^2
=sin(π+π/6 +x)+[cos[π-(π/6+x)]^2
=-sin(x+π/6) + [cos(x+π/6)]^2
=-sin(x+π/6) + {[1-[sin(x+π/6)]^2}
=-1/4+[1-(1/4)^2]
=-1/4+1-1/16
=11/16