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討論串[中學] 三角函數問題
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內容預覽:
2 2 (1/2). cosA=cosxcosC => sinA = (1-cos xcos C ). (sinA)^2+(sinB)^2+(sinC)^2. 2 2 2 2 2. = 1-cos xcos C + sin xsin C + sin C. 2 2 2 2 2 2. = 1-cos x
(還有148個字)
內容預覽:
sinθ. cosθ = tanθ = ------- => (cosθ)^2 = sinθ. cosθ. 1 - (sinθ)^2 = sinθ. (sinθ)^2 + sinθ - 1 = 0. -1 ±√5. sinθ = ----------. 2. -1 + √5. ∵ |sinθ|≦1
(還有479個字)