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cos7π/12sin35π/12sin(π/4-α)+cos(π/4-α)
题目详情
cos7π /12
sin35π/12
sin(π/4-α)+cos(π/4-α)
sin35π/12
sin(π/4-α)+cos(π/4-α)
▼优质解答
答案和解析
cos7π /12=cos105=-(根号6+根号2）/4
sin35π/12=(根号6+根号2）/4
sin(π/4-α)+cos(π/4-α)
=根号2/2(cosa-sina+sina+cosa)
=根号2*cosa
sin35π/12=(根号6+根号2）/4
sin(π/4-α)+cos(π/4-α)
=根号2/2(cosa-sina+sina+cosa)
=根号2*cosa
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