1、 1 18.1.1 1 2 P11-12 1 1 ABCD CD CDE AD=DE=CE E AE BE AEB A 1 B C D C D A B C=1 1 2 2 2 A 0 0 B 0 4 C 3 t+4 D 3 t N t ABCD N t A. 6 7 B. 7 8 C. 6 7 8 D. 6 8 9 1 ABCD AC 6 ABCD 7 AC A. 1 B. 2.5 C. 3.5 2 D. 9.5 2 ABCD 5 AC BD A. 2 4 B. 3 4 C. 4 5 D. 5 6 3 15min 1 ? ABCD AB/DC AD/BC ABCD ABCD AB/DC ,AD
2、/BC ABCD 3 ABCD AB/DC AD/BC 2 1 _ 2 _ _ ABCD AB CD CB AD B D BAD BCD ABCD AC ABC CDA 1 _ 2 _ ABCD DE AB BF CD E F AE=CF 4 ABCD A= C AD=CB AED= ADE CBF AE=CF , _ _ _ _ _ _ 1 2 1 ABCD 26cm AC BD O AC AB E BC AOD AOB 3cm AE A 3cm B 4cm C 5cm D 8cm 2 ABCD A m n B 2 -1 C -m -n D A -2 1 B -2 -1 C -1 -2 D -1 2 3 ABCD M CD DC=2AD AM BM 5 A B C D 4 2 5 28cm 5 ABCD E F DC BA AE CF AE CF BC AD G H EG=FH 4-6 2014 2014 6 1 B 2 D 3 A 1 B 2 A 3 C 4 2x 5x 2x+5x=14 x=2 10cm 4cm 10cm 4cm 5 ABCD AB CD AD BC AE CF AECF AGCH AE=CF AG=CH AG-AE=CH-CF EG=FH
