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標題:
數學題 triangle+inscribed circle
發問:
http://www.glowfoto.com/static_image/05-065000L/7518/gif/07/2010/img6/glowfoto (條數) ans: A=(square root 3) /4 <--唔識計 B= 6 CD= x^2+6x-24 =0 <--想知呢條equation 點來 E=( square root 33) -3 想要full solution,thanks!
圖片參考：http://img6.glowfoto.com/images/2010/07/05-0650007518L.gif 1) △AGD ~ △ADE , so AG/AD = AD/AE AD^2 = AG * AE x^2 = AG * AE ;;;; △ADF / (AG*AE) = (x^2)sin60° / (AG*AE) = sin60° = √3 / 2 for A 2) BD = BE and CF = CE so BC = BE + CE = BD + CF = 4 + 2 = 6 for B In △ABC , by cosine formula , cos60° = (AB^2 + AC^2 - BC^2)/(2AB AC) 1/2 = (x+4)^2 + (x+2)^2 - 6^2) / [2 (x+4)(x+2)] (x+4)(x+2) = (x+4)^2 + (x+2)^2 - 6^2 x^2 + 6x + 8 = x^2 + 8x + 16 + x^2 + 4x + 4 - 36 x^2 + 6x - 24 = 0 for C , D x = {- 6 +/- √[6^2 - 4(-24)]} / 2 x = - 3 + √33 for E or - 3 - √33 (rejected)
其他解答:
點解 △AGD ~ △ADE??
數學題 triangle+inscribed circle
發問:
http://www.glowfoto.com/static_image/05-065000L/7518/gif/07/2010/img6/glowfoto (條數) ans: A=(square root 3) /4 <--唔識計 B= 6 CD= x^2+6x-24 =0 <--想知呢條equation 點來 E=( square root 33) -3 想要full solution,thanks!
- {超急!!} 數學數學數學(10點)-@1@
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- 07 CE past paper@1@
- {超急!!} 數學數學數學(10點)-@1@
- 本人11碎Y打飛機唔射 射左=破處--@1@
- 赤柱藝墟是否在12月26日也開放？@1@
- 我想問08年飾金金價會否突破$9000- 1月份最高大概是-
- 07 CE past paper@1@
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最佳解答:圖片參考：http://img6.glowfoto.com/images/2010/07/05-0650007518L.gif 1) △AGD ~ △ADE , so AG/AD = AD/AE AD^2 = AG * AE x^2 = AG * AE ;;;; △ADF / (AG*AE) = (x^2)sin60° / (AG*AE) = sin60° = √3 / 2 for A 2) BD = BE and CF = CE so BC = BE + CE = BD + CF = 4 + 2 = 6 for B In △ABC , by cosine formula , cos60° = (AB^2 + AC^2 - BC^2)/(2AB AC) 1/2 = (x+4)^2 + (x+2)^2 - 6^2) / [2 (x+4)(x+2)] (x+4)(x+2) = (x+4)^2 + (x+2)^2 - 6^2 x^2 + 6x + 8 = x^2 + 8x + 16 + x^2 + 4x + 4 - 36 x^2 + 6x - 24 = 0 for C , D x = {- 6 +/- √[6^2 - 4(-24)]} / 2 x = - 3 + √33 for E or - 3 - √33 (rejected)
其他解答:
點解 △AGD ~ △ADE??
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