??:???ABCD???,

1
100??????????
???
?????
??
????????????????
???
2
????
?????????????????
???????????
?????????
??
??
??
3
???????????????
16.4.2?????
4
?????????????
??????????
??????
???????,????
??????????
??1????????
??2??????????, ??????????????
5
??????????
?????ABCD???, ABAD.
??ABBCCDDA.
??
????ABCD???
?ABBC(???????)
ABCD,ADBC(???????)
?ABBCCDDA.
????1?????????
6
????????????????????????
????ABCD?,???AC?BD????O.
??AC?BD AC???BAD??BCD
BD???ABC??ADC.
??
????ABCD???
?ABAD
(????????)
(??????????)
BOOD
??ABD?
?ABAD BOOD
?AC?BD,AC???BAD.
??AC???BCDBD???ABC??ADC.
????2?????????,??????????????

7
?
????
?????
????
??
?
?????
????
???? ????? ??
?
?
???
??ABCD?,???AC?BD????O
????
???????
??????
????,????
????,????
???????
???????
???,?4?Rt?, ?4??????
???????
?????????
8
??ABCD?,???????????
D
C
A
B
9
????
1.????(????) (1).???????????. (
) (2).???????????????. ( ) (3).???????????,????.
( ) (4).??????????. ( )

v


10
????
2.??ABCD? (1)???AB?6cm,??????_______. (2)??BDA
35,? ??????????
?______________________. (3)?????????? ?6?8,?????
?_______.
24cm
5
6
3
35
4
70?110 ?70?110
5
11
????
?1.
??1
??2
????,???ABCD?,
?AE?BC?E,AF?CD?F.
?CECF.
?E?F???BC?CD???.
??AEAF.
A
D
B
E
F
C
12
???1
????,???ABCD?,
??AEAF.
?????????????????????????????????.
13
???2
????,???ABCD?,?AE?BC?E,
AF?CD?F,?E?F???BC?CD???, ??EAF???.
14
????
???,??????????????? ??????????
15
????
1?????????????????????,??????????????????????????
??(?????)???(??).
2????????,????????????????????????????,?????????
?.
16
????
?? ??????58?(113?) ?????????

17
? ?