.
, .
:
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