. .
.
, 30 . 4 . .
.
. , KAB 30 . BK - , ABK - .
BK / AB = sin 30
sin 30 .
BK / AB = 1/2
BK - ,
4 / AB = 1/2
AB = 8
(), AB = CD = 8
, . , .
AB + CD = BC + AD
BC + AD = 8 + 8 = 16
.
: 16 .
- , , .
, .
, , 180.
360
ABCD , :
- 180
:
:
- ABCD ,
- ABCD
- ABCD
. ( ). , . , - . √ sqrt(), .
.
5 4, 42. .
.
, . a b.
:
S = 4a
S = 5b
P = 2a + 2b
|
|
4a = 5b
a = 5/4b
42 ,
2(5/4b) + 2b = 42
b = 9 1/3
a = 11 2/3
:
S = 4 * 11 2/3 = 5 * 9 1/3 = 46 2/3 2.
: 46 2/3 2.
.
16 . , , 3
.
, b, : = 2(+b).
- ,
b=3.
2(+3)=16
2*4=16
=2
=2, b=6.
: 2 6.
( 2)
NQ . , NBQ .
.
, . .
MAN PBQ . PB = AM , PQ = NM , BPQ NMA , NP MQ MP.
NBP QAM.
, NA = BQ, NB = BQ.
, , NBQ .
ABCD BD = 6 AD DC 60 . ABCD.
: ABMD, M - DC, ABMD.
.
ADB ( AD DC 60 ), DBC 60 , , AD BC, .
, BCD , 60 . , 180 , BCD 60 , , BCD - .
BCD - , BC = CD = BD = 6 .
, , 24 . .
:
CD, AB MD - , , ABMD - .
DAB 60 , , , .
ADM 120 , BD AD DC 60 , ADM .
M - DC, CM = MD. BM - DBC. , DBC - , , , . , DBM DBC 60 / 2 = 30 . ABM = 60 + 30 = 90 . BM - , BMD 90 .
, ABMD - .
: 24 . 60º, 90º, 90º, 120º - .
|
|
. ( ). , - . √ sqrt(), .
. : , " ".
:
- ,