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20 Anwendungen

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20.3 Vektorielle Darstellung der Ebene

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20.3.8 Lage zwischen zwei Ebenen

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Beispiel 20 - 225
Schnittgerade Ebene - Ebene bei Darstellung in Normalenform. .
Gegeben sei eine Ebene mit dem Ortsvektor .
r 1 → =( 1 0 1 ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabaGaaiaacaqaaeaadaqaaqaaaOqaamaaFiaabaGaam OCamaaBaaaleaacaaIXaaabeaaaOGaay51GaGaeyypa0ZaaeWaaeaa faqabeWabaaabaGaaGymaaqaaiaaicdaaeaacaaIXaaaaaGaayjkai aawMcaaaaa@3E51@ , dem Normalenvektor n 1 → =( 1 5 −3 ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabaGaaiaacaqaaeaadaqaaqaaaOqaamaaFiaabaGaam OBamaaBaaaleaacaaIXaaabeaaaOGaay51GaGaeyypa0ZaaeWaaeaa faqabeWabaaabaGaaGymaaqaaiaaiwdaaeaacqGHsislcaaIZaaaaa GaayjkaiaawMcaaaaa@3F41@
sowie eine Gerade mit dem Ortsvektor .

r 2 → =( 0 3 0 ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabaGaaiaacaqaaeaadaqaaqaaaOqaamaaFiaabaGaam OCamaaBaaaleaacaaIYaaabeaaaOGaay51GaGaeyypa0ZaaeWaaeaa faqabeWabaaabaGaaGimaaqaaiaaiodaaeaacaaIWaaaaaGaayjkai aawMcaaaaa@3E53@  und dem Normalenvektor    n 2 → =( 2 1 2 ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabaGaaiaacaqaaeaadaqaaqaaaOqaamaaFiaabaGaam OBamaaBaaaleaacaaIYaaabeaaaOGaay51GaGaeyypa0ZaaeWaaeaa faqabeWabaaabaGaaGOmaaqaaiaaigdaaeaacaaIYaaaaaGaayjkai aawMcaaaaa@3E51@ . .

Bestimmen Sie die Schnittgerade r(λ) → = r 0 → +λ a → MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabaGaaiaacaqaaeaadaqaaqaaaOqaamaaFiaabaGaam OCaiaacIcacqaH7oaBcaGGPaaacaGLxdcacqGH9aqpdaWhcaqaaiaa dkhadaWgaaWcbaGaaGimaaqabaaakiaawEniaiabgUcaRiabeU7aSn aaFiaabaGaamyyaaGaay51Gaaaaa@4570@  . .

.
man erhält  a → = n 1 → × n 2 → =( 1 5 −3 )×( 2 1 2 )=( 10+3 −6−2 1−10 )=( 13 −8 −9 ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabaGaaiaacaqaaeaadaqaaqaaaOqaamaaFiaabaGaam yyaaGaay51GaGaeyypa0Zaa8HaaeaacaWGUbWaaSbaaSqaaiaaigda aeqaaaGccaGLxdcacqGHxdaTdaWhcaqaaiaad6gadaWgaaWcbaGaaG OmaaqabaaakiaawEniaiabg2da9maabmaabaqbaeqabmqaaaqaaiaa igdaaeaacaaI1aaabaGaeyOeI0IaaG4maaaaaiaawIcacaGLPaaacq GHxdaTdaqadaqaauaabeqadeaaaeaacaaIYaaabaGaaGymaaqaaiaa ikdaaaaacaGLOaGaayzkaaGaeyypa0ZaaeWaaeaafaqabeWabaaaba GaaGymaiaaicdacqGHRaWkcaaIZaaabaGaeyOeI0IaaGOnaiabgkHi TiaaikdaaeaacaaIXaGaeyOeI0IaaGymaiaaicdaaaaacaGLOaGaay zkaaGaeyypa0ZaaeWaaeaafaqabeWabaaabaGaaGymaiaaiodaaeaa cqGHsislcaaI4aaabaGaeyOeI0IaaGyoaaaaaiaawIcacaGLPaaaaa a@620D@

. .
.
Die Ebenen sind nicht parallel, da   n 1 → × n 2 → ≠ 0 → MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabaGaaiaacaqaaeaadaqaaqaaaOqaamaaFiaabaGaam yyaaGaay51GaGaeyypa0Zaa8HaaeaacaWGUbWaaSbaaSqaaiaaigda aeqaaaGccaGLxdcacqGHxdaTdaWhcaqaaiaad6gadaWgaaWcbaGaaG OmaaqabaaakiaawEniaiabgcMi5oaaFiaabaGaaGimaaGaay51Gaaa aa@4704@

Einen Ortsvektor r0 → erhalten wir aus den beiden Ebenengleichungen: .
.
n1 →⋅(r0 →-r1 →) 1 5 -3 ⋅x0 - 1 y0 - 0 z0 - 1 = x0-1+5y0-3(z0-1) = 0.
und .
n2 →⋅(r0 →-r2 →) = 2 1 2 ⋅x0 - 0 y0 - 3 z0 - 0 = 2x0+y0-3+2z0 = 0. .
.
Wahl von x0 = 0: .
.
5y0-3z0=-2 y0 +2z0= 3 .
.

Auflösen ergibt y0 = 5 13 und z0 = 17 13. .
Daraus folgt die Geradengleichung .
.
r(λ) → = r 0 → +λ a → =( 0 5 13 17 13 )+λ( 13 −8 −9 )=( 13λ 5 13 −8λ 17 13 ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabaGaaiaacaqaaeaadaqaaqaaaOqaamaaFiaabaGaam OCaiaacIcacqaH7oaBcaGGPaaacaGLxdcacqGH9aqpdaWhcaqaaiaa dkhadaWgaaWcbaGaaGimaaqabaaakiaawEniaiabgUcaRiabeU7aSn aaFiaabaGaamyyaaGaay51GaGaeyypa0ZaaeWaaeaafaqabeWabaaa baGaaGimaaqaamaalaaabaGaaGynaaqaaiaaigdacaaIZaaaaaqaam aalaaabaGaaGymaiaaiEdaaeaacaaIXaGaaG4maaaaaaaacaGLOaGa ayzkaaGaey4kaSIaeq4UdW2aaeWaaeaafaqabeWabaaabaGaaGymai aaiodaaeaacqGHsislcaaI4aaabaGaeyOeI0IaaGyoaaaaaiaawIca caGLPaaacqGH9aqpdaqadaqaauaabeqadeaaaeaacaaIXaGaaG4mai abeU7aSbqaamaalaaabaGaaGynaaqaaiaaigdacaaIZaaaaiabgkHi TiaaiIdacqaH7oaBaeaadaWcaaqaaiaaigdacaaI3aaabaGaaGymai aaiodaaaaaaaGaayjkaiaawMcaaaaa@6590@ . .
.
Der Schnittwinkel errechnet sich wiederum über das Skalarprodukt:
.
φ = arccos n1 → ⋅n2 → |n1 →|⋅|n2 →|. .

Schnittwinkel: φ = arccos 1 5 -3 ⋅2 1 2 12 +52 +(-3)2⋅22 +12 +22
.
= arccos 2+5-6 35⋅9 = arccos 1 35⋅3 ≈ arccos 0, 056 ≈ 1, 51 ≈ 87o

.

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