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圖片ＬＩＮＫ： http://www.flickr.com/photos/harrykmb80_89b/7710261164/in/photostream 更新: 答案是60度，但是沒有步驟，我想要步驟，thanks。
最佳解答:
朋友你是不是發錯區了，你的題目該分類到「科學醫療 > 數學」 ============================================== 這題目的資料應該不足吧! Illegal proof: (聲明 - 唔好意思，我忘記哂d Thm既名...) Let...... x = ∠ACB a = ∠BAC b = ∠ABC α = ∠ACP β = ∠BCQ ---------------------------------------------------------------------------------------- Noted that...... [A] Use the property about parallel lines... >> (1) ---- a = α >> (2) ---- b = β [B] Use the property about circle, inscribed triangle & tangent... >> (3) ---- a = β >> (4) ---- b = α [C.1] Use the property about triangle... >> (5) ---- a + b + x = 180° [C.2] Use the property about straight line... >> (6) ---- α + β + x = 180° [C.3] Use again the property about parallel lines... >> (7) ---- a + (β + x) = 180° >> (8) ---- α + (b + x) = 180° ---------------------------------------------------------------------------------------- From eq. (1), (2), (3) and (4), a = α = b = β. Let y = a = α = b = β. Substitute y into anyone of eq. (5) to (8), we get... y + y + x = 180° We have reduced the system to one equation with two unknowns which is NOT solvable (has infinitely many solutions for infinitely many 0° ≤ y ≤ 90°). ∠ACB = 60° if and only if y = 60°. (i.e. ΔABC is a equilateral triangle, which is not a given source in the question.) ---------------------------------------------------------------------------------------- 所以，若要∠ACB = 60°，你要先證明ΔABC是等邊三角形...... 2012-08-11 04:13:55 補充： 也就是說，要證明 x = y。
其他解答:
已經提供題目的所有資料了嗎?
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中六數學，請解答，ＰＬＥＡＳＥ！發問:
圖片ＬＩＮＫ： http://www.flickr.com/photos/harrykmb80_89b/7710261164/in/photostream 更新: 答案是60度，但是沒有步驟，我想要步驟，thanks。
最佳解答:
朋友你是不是發錯區了，你的題目該分類到「科學醫療 > 數學」 ============================================== 這題目的資料應該不足吧! Illegal proof: (聲明 - 唔好意思，我忘記哂d Thm既名...) Let...... x = ∠ACB a = ∠BAC b = ∠ABC α = ∠ACP β = ∠BCQ ---------------------------------------------------------------------------------------- Noted that...... [A] Use the property about parallel lines... >> (1) ---- a = α >> (2) ---- b = β [B] Use the property about circle, inscribed triangle & tangent... >> (3) ---- a = β >> (4) ---- b = α [C.1] Use the property about triangle... >> (5) ---- a + b + x = 180° [C.2] Use the property about straight line... >> (6) ---- α + β + x = 180° [C.3] Use again the property about parallel lines... >> (7) ---- a + (β + x) = 180° >> (8) ---- α + (b + x) = 180° ---------------------------------------------------------------------------------------- From eq. (1), (2), (3) and (4), a = α = b = β. Let y = a = α = b = β. Substitute y into anyone of eq. (5) to (8), we get... y + y + x = 180° We have reduced the system to one equation with two unknowns which is NOT solvable (has infinitely many solutions for infinitely many 0° ≤ y ≤ 90°). ∠ACB = 60° if and only if y = 60°. (i.e. ΔABC is a equilateral triangle, which is not a given source in the question.) ---------------------------------------------------------------------------------------- 所以，若要∠ACB = 60°，你要先證明ΔABC是等邊三角形...... 2012-08-11 04:13:55 補充： 也就是說，要證明 x = y。
其他解答:
已經提供題目的所有資料了嗎?
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