Sin(x+派/2)=1/3则cos(x+7派/12)的值为?

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Sin(x+派/2)=1/3则cos(x+7派/12)的值为?

Sin(x+派/2)=1/3则cos(x+7派/12)的值为?
Sin(x+派/2)=1/3则cos(x+7派/12)的值为?

Sin(x+派/2)=1/3则cos(x+7派/12)的值为?
Sin(x+π/2)=cosx=1/3,则
sinx=土2√2/3,
cos(7π/12)=cos(π/3+π/4)=(√2-√6)/4,
sin(7π/12)=(√2+√6)/4,
∴cos(x+7π/12)=cosxcos(7π/12)-sinxsin(7π/12)
=(√2-√6)/12干(4+4√2)/12
=(-4-3√2-√6)/12,或(4+5√2-√6)/12.