-
304560sin cos tg 1ctg 1
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090180sin cos tg -ctg 0
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0 180
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sin (90- )=cos cos (90- )=sin
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150135120sin cos tg -1ctg -1
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a2=b2+c2- 2bc cosb2=a2+c2- 2ac cosc2=a2+b2- 2ab cos
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-
1 1 2 , 45. . =1, =2 , = 45 : = + 2 cos . =2+ 1 - 21 cos 45=5 =
5 -5 ( ) , =5: 5
12 45
-
2 M N, N= 8 , NK=7 , MK=3 . : NK = MN + MK 2MN MK cos M; 49 =
64+ 9 - 2 8 3 cos M ; 48 cos M=24; cos M=2448 =12, =60
: 60
N873
-
3 1 , 7 11 . . , (+1). : 72+112=2x2+2(x+1)2 49+121=2x2+2x2+4+2
4x2 +4-168=0 x2+-42=0 x1=6, x2=-7 x=-7 , =6, +1=7. , - 6 , 7. : 6 ,
7 .
x+1711
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( ) , , D , ADC ADB :
D1
2
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, =50, = 80, =72.
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: =180-(80+72)=28. :
: 48,3
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N . , =375, =400, =73, N=146.
-
:
= + 2 cos = 375+ 4002375 400 cos92 cos92= cos(90+2)=sin2=0,349
=195925 443 MN443-(73+146)224()
: 224
-
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ABD:
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=60 , =51, =63. . = 180 - (51 + 63) = 66. .
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