, , . (a2b) (a1b) .
180?.
.
∠(a2b) ∠(a1b) . b (a1a2) . ∠(a2b) + ∠(a1b) = ∠ (a1a2) = 180?. .. 180?. .
, .
.
∠(a2b) ∠(a1b) ∠(2d) ∠(1d) .
∠(a1b) = ∠(1d). , ∠(a1b) + ∠(a2b) =180 ∠(1d) + ∠(2d) =180. ∠(a1b) =180 - ∠(a2b) ∠(1d) =180 - ∠(2d). ∠(a1b) ∠(1d) , 180 - ∠(a2b) =180 - ∠(2d). , ∠(a2b) = ∠(2d). .
, 0, 90.
, 90, 180.
90, .
, .
, . ∠(a2b2) ∠(a1b1), ∠(a2b1) ∠(a1b2) .
.
.
.
∠(a2b2) ∠(a1b1) . (a2b1) ∠(a2b2) ∠(a1b1) 180, , ∠(a2b2) ∠(a1b1) . .
∠(a2b2) = ∠(a1b1), ∠(a2b1) = ∠(a1b2).
a b O.
a b AOB.
, ( ) ( ), .
AOB: ( ), ( ) ( ). . » . ∠. :
1. ∠, ∠;
2. ∠ ;
3. ∠(ab) a b .
. . .
, . D .
, , - . , ab .
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, . 180. , , .
.
(ab) (ac) (cb). ∠(ab) = ∠(ac) + ∠(cb).
, 180, .
, ( ) ( ), .
AOB: ( ), ( ) ( ). . » . ∠. :
1. ∠, ∠;
2. ∠ ;
3. ∠(ab) a b .
. . .
, . D .
, , - . , ab .
, . 180. , , .
.
(ab) (ac) (cb). ∠(ab) = ∠(ac) + ∠(cb).
, 180, .
, . Δ ABC Δ DEF .
, , . Δ PKM .
, . , . PK=PM=KM.
, . , .
(Δ A1B1C1 = Δ A2B2C2), . A1B1=A2B2, B1C1=B2C2, C1A1=C2A2 ∠ B1A1C1 = ∠ B2A2C2, ∠ A1B1C1 = ∠ A2B2C2, ∠ B1C1A1 = ∠ B2C2A2.
, .
, .
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(Δ A1B1C1 = Δ A2B2C2), . A1B1=A2B2, B1C1=B2C2, C1A1=C2A2 ∠ B1A1C1 = ∠ B2A2C2, ∠ A1B1C1 = ∠ A2B2C2, ∠ B1C1A1 = ∠ B2C2A2.
, .
, .
, , , , , .
B1D1 A1B1C1, B1. B2D2 A2B2C2, B2.
, , , .
EG FEH. ∠ FEG = ∠ GEH.
, , , .
RX SRT. SX = XT.
, .
. ABC A1B1C1 ∠ A = ∠ A1, AB = A1B1, AC = A1C1.
A1B2C2 ABC, B2, A1B1, 2 A1B1, 1.
A1B1=A1B2, B1 B2 .
∠ B1A1C1 = ∠ B2A1C2, A1C1 A1C2.
A1C1 = A1C2, 1 2. , A1B1C1 A1B2C2, , ABC. .