Trigonometria Exemplos
cos(6x)cos(6x)
Etapa 1
Um bom método para expandir cos(6x)cos(6x) é usando o teorema de De Moivre (r(cos(x)+i⋅sin(x))n=rn(cos(nx)+i⋅sin(nx)))(r(cos(x)+i⋅sin(x))n=rn(cos(nx)+i⋅sin(nx))). Quando r=1r=1, cos(nx)+i⋅sin(nx)=(cos(x)+i⋅sin(x))ncos(nx)+i⋅sin(nx)=(cos(x)+i⋅sin(x))n.
cos(nx)+i⋅sin(nx)=(cos(x)+i⋅sin(x))ncos(nx)+i⋅sin(nx)=(cos(x)+i⋅sin(x))n
Etapa 2
Expanda o lado direito de cos(nx)+i⋅sin(nx)=(cos(x)+i⋅sin(x))ncos(nx)+i⋅sin(nx)=(cos(x)+i⋅sin(x))n usando o teorema binomial.
Expandir: (cos(x)+i⋅sin(x))6(cos(x)+i⋅sin(x))6
Etapa 3
Use o teorema binomial.
cos6(x)+6cos5(x)(isin(x))+15cos4(x)(isin(x))2+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)(isin(x))+15cos4(x)(isin(x))2+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4
Etapa 4.1
Simplifique cada termo.
Etapa 4.1.1
Aplique a regra do produto a isin(x)isin(x).
cos6(x)+6cos5(x)isin(x)+15cos4(x)(i2sin2(x))+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)+15cos4(x)(i2sin2(x))+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.2
Reescreva usando a propriedade comutativa da multiplicação.
cos6(x)+6cos5(x)isin(x)+15⋅i2cos4(x)sin2(x)+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)+15⋅i2cos4(x)sin2(x)+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.3
Reescreva i2i2 como -1−1.
cos6(x)+6cos5(x)isin(x)+15⋅-1cos4(x)sin2(x)+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)+15⋅−1cos4(x)sin2(x)+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.4
Multiplique 1515 por -1−1.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)+20cos3(x)(isin(x))3+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.5
Aplique a regra do produto a isin(x)isin(x).
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)+20cos3(x)(i3sin3(x))+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)+20cos3(x)(i3sin3(x))+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.6
Reescreva usando a propriedade comutativa da multiplicação.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)+20⋅i3cos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)+20⋅i3cos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.7
Fatore i2i2.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)+20⋅(i2⋅i)cos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)+20⋅(i2⋅i)cos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.8
Reescreva i2i2 como -1−1.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)+20⋅(-1⋅i)cos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)+20⋅(−1⋅i)cos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.9
Reescreva -1i−1i como -i−i.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)+20⋅(-i)cos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)+20⋅(−i)cos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.10
Multiplique -1−1 por 2020.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)−20icos3(x)sin3(x)+15cos2(x)(isin(x))4+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.11
Aplique a regra do produto a isin(x)isin(x).
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)(i4sin4(x))+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)−20icos3(x)sin3(x)+15cos2(x)(i4sin4(x))+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.12
Reescreva usando a propriedade comutativa da multiplicação.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15⋅i4cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)−20icos3(x)sin3(x)+15⋅i4cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.13
Reescreva i4i4 como 11.
Etapa 4.1.13.1
Reescreva i4i4 como (i2)2(i2)2.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15⋅(i2)2cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)−20icos3(x)sin3(x)+15⋅(i2)2cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.13.2
Reescreva i2i2 como -1−1.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15⋅(-1)2cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)−20icos3(x)sin3(x)+15⋅(−1)2cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.13.3
Eleve -1−1 à potência de 22.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15⋅1cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)−20icos3(x)sin3(x)+15⋅1cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15⋅1cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)−20icos3(x)sin3(x)+15⋅1cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.14
Multiplique 1515 por 11.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6cos6(x)+6cos5(x)isin(x)−15cos4(x)sin2(x)−20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)(isin(x))5+(isin(x))6
Etapa 4.1.15
Aplique a regra do produto a isin(x).
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)(i5sin5(x))+(isin(x))6
Etapa 4.1.16
Fatore i4.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)(i4isin5(x))+(isin(x))6
Etapa 4.1.17
Reescreva i4 como 1.
Etapa 4.1.17.1
Reescreva i4 como (i2)2.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)((i2)2isin5(x))+(isin(x))6
Etapa 4.1.17.2
Reescreva i2 como -1.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)((-1)2isin5(x))+(isin(x))6
Etapa 4.1.17.3
Eleve -1 à potência de 2.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)(1isin5(x))+(isin(x))6
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)(1isin5(x))+(isin(x))6
Etapa 4.1.18
Multiplique i por 1.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)(isin5(x))+(isin(x))6
Etapa 4.1.19
Aplique a regra do produto a isin(x).
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)+i6sin6(x)
Etapa 4.1.20
Fatore i4.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)+i4i2sin6(x)
Etapa 4.1.21
Reescreva i4 como 1.
Etapa 4.1.21.1
Reescreva i4 como (i2)2.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)+(i2)2i2sin6(x)
Etapa 4.1.21.2
Reescreva i2 como -1.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)+(-1)2i2sin6(x)
Etapa 4.1.21.3
Eleve -1 à potência de 2.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)+1i2sin6(x)
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)+1i2sin6(x)
Etapa 4.1.22
Multiplique i2 por 1.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)+i2sin6(x)
Etapa 4.1.23
Reescreva i2 como -1.
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)-1sin6(x)
Etapa 4.1.24
Reescreva -1sin6(x) como -sin6(x).
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)-sin6(x)
cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)-sin6(x)
Etapa 4.2
Reordene os fatores em cos6(x)+6cos5(x)isin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6cos(x)isin5(x)-sin6(x).
cos6(x)+6icos5(x)sin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6icos(x)sin5(x)-sin6(x)
cos6(x)+6icos5(x)sin(x)-15cos4(x)sin2(x)-20icos3(x)sin3(x)+15cos2(x)sin4(x)+6icos(x)sin5(x)-sin6(x)
Etapa 5
Retire as expressões com a parte imaginária, que são iguais a cos(6x). Remova o número imaginário i.
cos(6x)=cos6(x)-15cos4(x)sin2(x)+15cos2(x)sin4(x)-sin6(x)