. ( ). , . , - . √ sqrt(), .
ABC AB, AC 13. B 3/4. AK, BC .
.
B, AKB
AK/KB = tg B = 3/4
.
:
(3x)2 + (4x)2 = (13a)2
9x2 + 16x2 = 169a2
25x2 = 169a2
x2 = 169/25a2
x = 13/5a
AK = 3x = 13/5a*3= 7,8a
KB = 4x = 13/5a*4 = 10,4a
: 7,8a 10,4a
,
.
4 MNK MK MN . , 5 CN.
.
CN = x, MN = 5. a = 5x
.
,
d = p - c
x = a + b/2 - a
x = b/2
b = 2x
a b .
r = x√(2/3)
4 = x√(2/3)
x = 4 / √(2/3)
a = 5x = 20 / √(2/3)
: 20 / √(2/3)
,
, , :
:
a,b,c -
S -
α - , a
,
. , . , - .
AB BC, . ABC.
.
, O, AO, BO CO. AB BC , AO, BO CO , ABO AB=AO=BO=r ( ), BCO BC=OC=OB=r ( ).
, ABO BCO - . 60 . ABO=OBC=600, ABC ABO OBC, ABC = ABO + OBC = 600 + 600= 1200.
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: ABC, AB BC 120 .
26 . .
.
. R = 26/2 = 13 .
: 13 .
=60 , 1, √7. .
.
BC x, AB = x+1
,
R = a / 2sinα
a - , α
, , sin 60 √3/2:
√7 = AC / 2sin60º
√7 = AC / (2 √3/2)
√7 = AC / √3
AC = √21
, ( 2)
. ( , , , ). , - . √ sqrt(), .
.
, ABC, √3 .
B, AC =√6
.
,
R = a / 2sinα,
a - , , α - .
:
√3 = √6 / 2sinα
2sinα = √2
sinα = √2/2
,
α = 45º
: , 45 .