CKMN C, KM E, KE 3 ME. MN, CKMN 51 .
.
CE - , KCE 90 / 2 = 45 .
CKE KEC , 180 . ( - , KEC 45 ), 180 - 90 - 45 = 45 .
CKE , . CK=KE=MN.
KE x. EM +3. ,
2 (CK + KE + EM) = 51
, CK = KE
2 (x + x + x + 3) = 51
2(3x + 3) = 51
6x + 6 = 51
6x = 45
x = 7,5
KE = CK = MN, MN = 7,5
: 7,5
32 , , - 260 . .
.
x y.
:
2(x+y)=32
(, , )
2x2+2y2=260
. ,
x+y=16
x=16-y
, x .
2(16-y)2+2y2=260
2(256-32y+y2)+2y2=260
512-64y+4y2-260=0
4y2-64y+252=0
.
D=4096-16x252=64
x1=9
x2=7
, , x+y=16 (. ) x=9, y=7 , x=7, y=9
: 7 9
26 , , , 89 . . .
.
x y.
:
2(x+y)=26
(, , , )
x2+y2=89
. ,
x+y=13
y=13-y
, x .
(13-y)2+y2=89
169-26y+y2+y2-89=0
2y2-26y+80=0
.
D=676-640=36
x1=5
x2=8
, , x+y=13 (. ) x=5, y=8 , x=8, y=5
: 5 8
26 2 3.
.
x. :
2(2x+3x)=26
2x+3x=13
5x=13
x=13/5
, , :
2x*3x=2*13/5*3*13/5=40,56 2
|
|
. ( ). , - . √ sqrt(), .
.
25%. , ?
.
S = ab
25%, a2 = 1,25a. ,
S2 = 1,25ab
, , ,
S2 = S / 1.25
S2 = 1,25ab / 1.25
,
S2 = (1,25a) b / 1.25
1 / 1,25 = 0,8
, (1 - 0,8) * 100% = 20%
: 20%.
. √ . - "/".
, . , 30 - sin () "30 ", - . 60 , 60 ..
α () | |||||||||||||
α | π/12 | π/6 | π/4 | π/3 | 5π/12 | π/2 | 2π/3 | 3π/4 | 5π/6 | π | 3π/2 | 2π | |
sin () | 1/2 | √2/2 | √3/2 | √3/2 | √2/2 | 1/2 | -1 | ||||||
cos () | √3/2 | √2/2 | 1/2 | -1/2 | -√2/2 | -√3/2 | -1 | ||||||
tg () | 2 - √3 | 1/√3 | √3 | 2 + √3 | - | -√3 | -1 | -√3/3 | - | ||||
ctg () | - | 2 + √3 | √3 | 1/√3 | 2 - √3 | -√3/3 | -1 | -√3 | - | - | |||
sec () | 2/√3 | √2 | - | -√2 | -1 | - | |||||||
cosec () | - | √2 | 2/√3 | √2 | - | -1 | - |
( (tg) 90 , (ctg) 180 ) .