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1. .
1. P 1 = 10 H P 2 = 25 H, α = 60˚. , (.1).
. :
R 2 = P + P 2 P 1 P 2 cos(180˚ α);
R = .
.
sin = sin α = = 0,694;
sin = sin α = = 0,277;
44˚; 16˚.
2. : P 1 = 3 H, P 2 = 5 H, P 3 = 6 H, P 4 = 7 H, P 5 = 2 H (. 2), α = 45˚.
. x y:
P x = P 5 + P 2cos α + P 3 = 2 + + 6 = 7,54 ;
P y = P 1 P 4 + P 2sin α = 3 7 + 3,54 = 0,46 .
:
R = 7,54 .
3. B ABC (. 3) P 1 = 20 H P 2 = 15 H. AB BC, , α = 30˚.
. . - RA RC.
xBy:
; RA P 2cos α RC cos α = 0;
; P 2sin α RC sin α P 1 = 0.
RC = 25 , RA = 8,7 . , , .
4. , 1 2 (.4), G =100 H. l = 1 . a 1 , 20 ?
. 1 2 R 1 R 2 . R 1 20 . G : G = R 1 + R 2.
R 2 = G R 1 = 80 .
,
a = = = 0,8 .
5. (. 5). , = 2 .
. xAy. . , . () RB .
, q . , , /. q = dQ/dx. : Q =
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, . (. 5).
:
, M Pa + RB 2 a (qa) 2,5 a = 0,
PA PA + RB 2 a a a = 0, RB =5 = 10 .
;
RA + RB qa = 0;
RA + 5 4 = 0;
RA = 0.
6. , , 1, 2; 3 (. 6). , 1 = 2 , 2 = 2 , 3 = 4 , α = 45˚.
. xAy. , RA , Y m.
; + P 1 2sin α = 0; 0,41 ;
; Y P 3 2cos α = 0; Y 5,41 ;
; P14 + 2sin α 3 + m A = 0; m A = 3,76 .
, m A . 6.
7. l = 4 ( = 45˚), = 20 , (. 7). , α = 45˚.
. . R A X , R A Y , R A Z R B R B X , R B Z . R K , z
R Z = R K sin α = R K ,
x, y :
R X = R Y = R K sin α cos = R K /2.
:
; RA + RB R X = 0;
; RA Y R Y = 0;
; RAZ P + RKZ + R BZ = 0;
; + R BZ + R KZ = 0;
; R KZ = 0;
; R BX = 0.
RA = RAY = P ; RAZ = ;
RB = RBZ = 0;
RK = RKY = P ; RKZ = .
8. (. 8) 2 l = 100 . , : Ft = 100 , FR = 37 , Fa = 18 . d = 200 . m .
. . , RA, RAY. : RB , RBY, RBZ.
:
; FR RX RX = 0;
; RA Y + RBY Ft = 0;
; RBZ Fa = 0;
; RAY 2 Ft = 0;
; RAX 2 Fa FR = 0;
; m F t = 0.
m = 10 ; RA = 0,5 H; RAY = 50 H;
RB = 36,5 H; RBY = 50 H; RBZ = 18 H.
9. , (. 9).
. : , 2 3, . :
F 1 = 300 600 = 18 104 2 ;
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F 2 = = 4,5 104 2 ;
F 3 = = 3,14 104 2 .
. : 1= 300 , 1 = 150 , 2 = 100 , 2= 400, 3 = 150 , 3 = 150 .
:
yc = ;
c = .
1.