L-12-Autmn2017 (824153), страница 2
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. . , bn ). ®£¤ ª®®à¤¨ âë ¢¥ªâ®à AB ¢ á¨á⥬ å ª®®à¤¨ â(x1 , . . . , xn ), (x1 , . . . , xn ) ᮮ⢥âá⢥® à ¢ë b − a, b − a ¨ á¢ï§ ë ¬¥¦¤ã ᮡ®©¯® ä®à¬ã«¥ (12.6) à ¢¥á⢮¬ b − a = C (b − a ), ¨ ¬ë ¨¬¥¥¬−→ −→hAB, ABi = hb − a, b − ai = hC (b − a ), C (b − a )i= hb − a , b − a i = hb − a , b − a ie~−→ −→= hAB, ABie~. áá㦤 ï ª ª ¢ëè¥, ¬ë ¯®«ãç ¥¬−→ −−→hAB, AW i = hb − a, w − ai = hC (b − a ), C (w − a )i= hb − a , w − a i = hb − a , w − a ie~−→ −−→= hAB, AW ie~.¥7«¥¤á⢨¥ 12.4 à⮣® «ì ï § ¬¥ ª®®à¤¨ â ¥ ¬¥ï¥â ã£«ë ¬¥¦¤ã ¢¥ª-â®à ¬¨ ¨ à ááâ®ï¨ï ¬¥¦¤ã â®çª ¬¨.−→®ª § ⥫ìá⢮.
¯®¬¨¬, çâ® d(A, B ) = |AB|, cos ∠BAW =−→ −−→hAB,AW i−→ −−→|AB||AW |.¥à⮣® «ìë¥ (n × n)-¬ âà¨æë, n = 1, 2n=1. ®ïâ®, çâ® O(1) | íâ® â ª¨¥ ç¨á« c, çâ®SO(1) = {1}.n=2. «ï ¤¢ã¬¥àëå ®à⮣® «ìë¬ ¬ âà¨æµc11c12c21c22¶µc11c21c12c22¶µ=µc211 + c221c11 c12 + c21 c22c11c12c2c21c22= 1⇒ O(1)={−1, 1},¶¬ë ¨¬¥¥¬c11 c12 + c21 c22c212 + c222¶µ= 10 01¶,®âªã¤ á«¥¤ã¥â, çâ® c11 = cos α, c21 = sin α, c12 = cos β , c22 = sin β ¤«ï ¥ª®â®àëåç¨á¥« α, β ; ¯à¨ í⮬ cos α cos β + sin α sin β = 0 ⇔ cos(β − α) = 0 (ä®à¬ã« ª®á¨ãá à §®á⨠¢ë¢®¤¨« áì à ¥¥). «¥¤®¢ ⥫ì®, β = α + π2 ¨«¨ β = α + 32π . ª¨¬®¡à §®¬½µO(2) =cos αsin α− sin αcos α«¥¤®¢ ⥫ì®,½µSO(2) =¶µ,cos α0sin α0cos αsin α− sin αcos αsin α0− cos α0¶¶¾,0α, α ∈ R .¾,α∈R .¥®¬¥âà¨ç¥áª¨ ¥§ ¢¨á¨¬ë¥ â®çª¨ãáâì A0 , A1 , . .
. , Ar ∈ V ää , dim V ää = n, | ¥ª®â®àë¥ â®çª¨. «ï ª ¦¤®£®i ∈ {0, . . . , r} ¢¢¥¤¥¬ ¢ à áᬮâ२¥ á«¥¤ãî騥 ¢¥ªâ®àë¥ ¯®¤¯à®áâà á⢠Vi−−−→−−−→= L(Ai A0 , . . . , Ai Ar ). 䨪á¨à㥬 i, ⮣¤ ¤«ï «î¡®£® j = 0, . . . , r ¬ë ¨¬¥¥¬−−−→ −−−→ −−−→−−−→ −−−→Ai Aj = Ai A0 + A0 Aj = −A0 Ai + A0 Aj .−−−→−−−→ ª¨¬ ®¡à §®¬, á¨á⥬ ¢¥ªâ®à®¢ {A0 A1 , . . . , A0 Ar } ï¥âáï ¯®«®© á¨á⥬®© ¢¥ªâ®à®¢ ¤«ï Vi , ⮣¤ ¯® «¥¬¬¥ F ¨§ «¥ªæ¨¨ ü3 ¬ë ¯®«ãç ¥¬, çâ® dim Vi ≤ dim V0 .® â®ç® â ª¦¥ ¬ë ¬®¦¥¬ ¯à¨©â¨ ª ¢ë¢®¤ã, çâ® dim V0 ≤ dim Vi .
ª¨¬ ®¡à §®¬, dim V1 = · · · = dim Vr = dim V0 = pr , £¤¥ pr | ¬ ªá¨¬ «ì®¥ ç¨á«® «¨¥©®−−−→−−−→¥§ ¢¨á¨¬ëå ¢¥ªâ®à®¢ ¨§ {A0 A1 , . . . , A0 Ar }.¯à¥¤¥«¥¨¥ 12.2. ᫨ pr = r, â® â®çª¨ A0 , A1 , . . . , Ar §ë¢ îâáï £¥®¬¥âà¨ç¥áª¨ ¥§ ¢¨á¨¬ë¬¨ ¢ V ää ..