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. 10 , 13 .




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, .
:

S = 5 sqrt ((13 + 5) (13 - 5))
S = 5 √ 144 = 60

, 60 * 4 = 240 2

, KN = 10/2 = 5
, , , , CN = 10/2 = 5

ON2 + CN2 = OC2
ON2 + 25 = 169
ON2 = 144
ON = 12

OK2+ KN2= ON2
OK2 + 25 = 144
OK = √119

: √119, 240 2.

( 3)

. ( , ). , - . " " sqrt(), sqrt - , . "√".

.
10 . , 60.

.

ONK 60 ,
KN = ON cos 60 = 10 * 1/2 = 5

, , , K - , .

AD = 2KN = 2 * 5 = 10

,

S1 = AD2 = 102 = 100 2.


S2 = 1/2 CD * ON
S2 = 1/2 * 10 * 10 = 50 2.


S = S1 + 4S2 = 100 + 4 * 50 = 300 2.

: 300 2.

. ( , ). , - . " " sqrt(), sqrt - , . "√".

, 3.
.

.

.
, , , - . , - . KN = /2

OKN - , OK - , 3.
KNO, α.

tg α = OK / KN
tg α = 3a / (a/2) = 6
α = arctg 6 ≈ 80.5377

.
√2. , .

, OKC KCO ( β)

tg β = OK / KC
tg β = 3a / (√2/2) = 6 / √2
β = arctg 6/√2 ≈ 76.7373

: arctg 6 ≈ 80.5377; arctg 6/√2 ≈ 76.7373





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