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[ Math ]
討論串[中學]
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純幾何解法:. 過E做AB的平行線交BC於C'. 過D做BC的平行線交AC於D',過C做BA的平行線,此兩線相交於H. BH交AC於I. CD垂直BH於O. D對AD'做垂足O'. ∠CIB = 60 = ∠DIE. △IDO' = △ICO => OC = O'D. => △OCB = △O'DE
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draw CD, we have angle BCD = 50deg and angle DCE = 30 deg. let BC = 1, CD = x, AC = y. 1/sin50 = x/sin80. x = sin80/cos40 = 2sin40. 1/sin30 = x/sin(DE
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表弟來玩 求我幫他但是我也離開學校很久. 可以求個各位的幫助嗎 解法跟答案. https://i.imgur.com/l5hJHsn.jpg. https://i.imgur.com/FDxd37K.jpg. https://i.imgur.com/beCee03.jpg. https://i.im
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