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共回答了23个问题采纳率:82.6% 举报
sinθ+cosθ=1/3,cosθ=1/3-sinθ
(sinθ)^2+(cosθ)^2=1
(sinθ)^2+(1/3-sinθ)^2=1
(sinθ)^2+1/9-2/3*sinθ+(sinθ)^2=1
2(sinθ)^2-2/3*sinθ-8/9=0
(sinθ)^2-1/3*(sinθ)-4/9=0
(sinθ-1/6)^2-1/36-4/9=0
(sinθ-1/6)^2=17/36 θ∈﹙0,π﹚,sinθ>0
sinθ=1/6+(根号17)/6=(1+根号17)/6,或sinθ=1/6-(根号17)/6=(1-根号17)/6
1年前
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