, .
1 3, 2 4 - . 2 1, 3. 1 + 2 =1800 3 + 2 =1800. : 1=1800-2, 3=1800-2. , 1 3 . , . , .
2. .
, .
, .
3. , .
1 :
111, =11, =11, 1 . , =111.
()=()1, 111 , 1, 11 11. =11, =11, 11, - 11; , 1, 1. , 11. , 111 , .
3. .
, , .
, , D .
D D ( 2 : AD ; 1 2 .. AD-; AB=AC, .. ) , D = DC 3 = 4. D = DC , D D . 3 4 , . , . .
4. -> . ( )
5. ..-> ( )
, .
, 1=2.
2 3 , 2=3. , 1=3. 1 3 , . .
6. .
1800.
, ++=1800.
, . 1 4 , 3 5 . (1)4=1; 5=3.
|
|
, 4, 2 5 , .. 4+2+5=1800. , (1), : 1+2+3=1800 ++=1800..
7. .