演繹幾何(2)..幾何高手入

３ angle BAD = angle CAD (AD is an angle bisector of triangle ABC) AD = AD (common side) angle ADB = angle ADC ＝　９０　ｄｅｇｒｅｅ　（ＡＤ　ｉｓ　ｐｅｒｐｅｎｄｉｃｕｌａｒ　ｔｏ　ＢＣ） triangle　ＡＤＢ　ａｎｄ triangle ＡＤＣ　ａｒｅ　ｃｏｎｇｒｕｅｎｔＢＤ　＝　ＣＤ　　　（ｃｏｒｒｅｓｐｏｎｄｉｎｇ　ｓｉｄｅｓ　ｏｆ　ｃｏｎｇｒｕｅｎｔ triangleｓ） ∴　ＡＤ　ｉｓ　ａ　Ｍｅｄｉａｎ　ｏｆ　triangle ABC ４ＰＱ　＝　ＰＲ　（ｐｒｏｐｅｒｔｉｅｓ　ｏｆ　ｅｑｕｉｌａｔｅｒａｌ　triangle）ＱＭ= RM (PM ｉｓ　ａ　Ｍｅｄｉａｎ　ｏｆ　triangle PQR) angle QPM = angle RPM (ｐｒｏｐｅｒｔｉｅｓ of isosceles triangle) ∴ PM ia an angle bisector of triangle PQR Note : Given triangle PQR is an isosceles triangle, and PQ = PR and ONLY ONE of following conditions 1. PM ｉｓ　ａ　Ｍｅｄｉａｎ　ｏｆ　triangle PQR 2. PM ｉｓ　ｐｅｒｐｅｎｄｉｃｕｌａｒ　ｔｏ　QR 3. angle QPM = angle RPM or PM is an angle bisector of triangle QPR then the other 2 conditions can be proved. (ｐｒｏｐｅｒｔｉｅｓ of isosceles triangle) PQ = PR (已知) 和 1. QM = RM 2.PM 垂直 QR 3.角QPM = 角RPM 1,2,3 任何一樣其它1,2,3剩下二樣可成立理由(等腰△性質)

2009-12-02 11:45:19 補充：
多謝liuholap君指正,呢度我漏咗
triangle　ＡＤＢ　ａｎｄ triangle ＡＤＣ　ａｒｅ　ｃｏｎｇｒｕｅｎｔＢＤ　(ASA)

ＡＤＢ　ａｎｄ triangle ＡＤＣ　ａｒｅ　ｃｏｎｇｒｕｅｎｔＢＤ　＝　ＣＤ　　　（ｃｏｒｒｅｓｐｏｎｄｉｎｇ　ｓｉｄｅｓ　ｏｆ　ｃｏｎｇｒｕｅｎｔ triangleｓ）

呢度我唔明 .咩意思啊. 同埋唔洗證明 例如 SSS SAS個d?

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