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Popular Trigonometria >

4sin^2(x)=8sin^2(x/2)

Solução

4 sin^{2} (x) = 8 sin^{2} (\frac{x}{2})

Solução

x = 4 πn, x = 2 π + 4 πn, x = \frac{3 π}{2} + 4 πn, x = \frac{5 π}{2} + 4 πn, x = \frac{π}{2} + 4 πn, x = \frac{7 π}{2} + 4 πn

Graus

x = 0^{\circ} + 72 0^{\circ} n, x = 36 0^{\circ} + 72 0^{\circ} n, x = 27 0^{\circ} + 72 0^{\circ} n, x = 45 0^{\circ} + 72 0^{\circ} n, x = 9 0^{\circ} + 72 0^{\circ} n, x = 63 0^{\circ} + 72 0^{\circ} n

Passos da solução

4 sin^{2} (x) = 8 sin^{2} (\frac{x}{2})

Subtrair

8 sin^{2} (\frac{x}{2})

de ambos os lados

4 sin^{2} (x) - 8 sin^{2} (\frac{x}{2}) = 0

Sea:

u = \frac{x}{2}

4 sin^{2} (2 u) - 8 sin^{2} (u) = 0

Fatorar

4 sin^{2} (2 u) - 8 sin^{2} (u) : 4 (sin (2 u) + 2 sin (u)) (sin (2 u) - 2 sin (u))

4 sin^{2} (2 u) - 8 sin^{2} (u)

Reescrever

- 8

como

2 \cdot 4

= 4 sin^{2} (2 u) + 2 \cdot 4 sin^{2} (u)

Fatorar o termo comum

4

= 4 (sin^{2} (2 u) - 2 sin^{2} (u))

Fatorar

sin^{2} (2 u) - 2 sin^{2} (u) : (sin (2 u) + 2 sin (u)) (sin (2 u) - 2 sin (u))

sin^{2} (2 u) - 2 sin^{2} (u)

Reescrever

sin^{2} (2 u) - 2 sin^{2} (u)

como

sin^{2} (2 u) - (2 sin (u))^{2}

sin^{2} (2 u) - 2 sin^{2} (u)

Aplicar as propriedades dos radicais:

a = (a)^{2}

2 = (2)^{2}

= sin^{2} (2 u) - (2)^{2} sin^{2} (u)

Aplicar as propriedades dos expoentes:

a^{m} b^{m} = (ab)^{m}

(2)^{2} sin^{2} (u) = (2 sin (u))^{2}

= sin^{2} (2 u) - (2 sin (u))^{2}

= sin^{2} (2 u) - (2 sin (u))^{2}

Aplicar a regra da diferença de quadrados:

x^{2} - y^{2} = (x + y) (x - y)

sin^{2} (2 u) - (2 sin (u))^{2} = (sin (2 u) + 2 sin (u)) (sin (2 u) - 2 sin (u))

= (sin (2 u) + 2 sin (u)) (sin (2 u) - 2 sin (u))

= 4 (sin (2 u) + 2 sin (u)) (sin (2 u) - 2 sin (u))

4 (sin (2 u) + 2 sin (u)) (sin (2 u) - 2 sin (u)) = 0

Resolver cada parte separadamente

sin (2 u) + 2 sin (u) = 0 or sin (2 u) - 2 sin (u) = 0

sin (2 u) + 2 sin (u) = 0 : u = 2 πn, u = π + 2 πn, u = \frac{3 π}{4} + 2 πn, u = \frac{5 π}{4} + 2 πn

sin (2 u) + 2 sin (u) = 0

Reeecreva usando identidades trigonométricas

sin (2 u) + sin (u) 2

Utilizar a identidade trigonométrica do arco duplo:

sin (2 x) = 2 sin (x) cos (x)

= 2 sin (u) cos (u) + 2 sin (u)

sin (u) 2 + 2 cos (u) sin (u) = 0

Fatorar

sin (u) 2 + 2 cos (u) sin (u) : sin (u) (2 + 2 cos (u))

sin (u) 2 + 2 cos (u) sin (u)

Fatorar o termo comum

sin (u)

= sin (u) (2 + 2 cos (u))

sin (u) (2 + 2 cos (u)) = 0

Resolver cada parte separadamente

sin (u) = 0 or 2 + 2 cos (u) = 0

sin (u) = 0 : u = 2 πn, u = π + 2 πn

sin (u) = 0

Soluções gerais para

sin (u) = 0

sin (x)

tabela de periodicidade com ciclo de

2 πn

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

u = 0 + 2 πn, u = π + 2 πn

u = 0 + 2 πn, u = π + 2 πn

Resolver

u = 0 + 2 πn : u = 2 πn

u = 0 + 2 πn

0 + 2 πn = 2 πn

u = 2 πn

u = 2 πn, u = π + 2 πn

2 + 2 cos (u) = 0 : u = \frac{3 π}{4} + 2 πn, u = \frac{5 π}{4} + 2 πn

2 + 2 cos (u) = 0

Mova

2

para o lado direito

2 + 2 cos (u) = 0

Subtrair

2

de ambos os lados

2 + 2 cos (u) - 2 = 0 - 2

Simplificar

2 cos (u) = - 2

2 cos (u) = - 2

Dividir ambos os lados por

2

2 cos (u) = - 2

Dividir ambos os lados por

2

\frac{2 cos ( u )}{2} = \frac{- 2}{2}

Simplificar

cos (u) = - \frac{2}{2}

cos (u) = - \frac{2}{2}

Soluções gerais para

cos (u) = - \frac{2}{2}

cos (x)

tabela de periodicidade com ciclo de

2 πn

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

u = \frac{3 π}{4} + 2 πn, u = \frac{5 π}{4} + 2 πn

u = \frac{3 π}{4} + 2 πn, u = \frac{5 π}{4} + 2 πn

Combinar toda as soluções

u = 2 πn, u = π + 2 πn, u = \frac{3 π}{4} + 2 πn, u = \frac{5 π}{4} + 2 πn

sin (2 u) - 2 sin (u) = 0 : u = 2 πn, u = π + 2 πn, u = \frac{π}{4} + 2 πn, u = \frac{7 π}{4} + 2 πn

sin (2 u) - 2 sin (u) = 0

Reeecreva usando identidades trigonométricas

sin (2 u) - sin (u) 2

Utilizar a identidade trigonométrica do arco duplo:

sin (2 x) = 2 sin (x) cos (x)

= 2 sin (u) cos (u) - 2 sin (u)

- sin (u) 2 + 2 cos (u) sin (u) = 0

Fatorar

- sin (u) 2 + 2 cos (u) sin (u) : sin (u) (- 2 + 2 cos (u))

- sin (u) 2 + 2 cos (u) sin (u)

Fatorar o termo comum

sin (u)

= sin (u) (- 2 + 2 cos (u))

sin (u) (- 2 + 2 cos (u)) = 0

Resolver cada parte separadamente

sin (u) = 0 or - 2 + 2 cos (u) = 0

sin (u) = 0 : u = 2 πn, u = π + 2 πn

sin (u) = 0

Soluções gerais para

sin (u) = 0

sin (x)

tabela de periodicidade com ciclo de

2 πn

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

u = 0 + 2 πn, u = π + 2 πn

u = 0 + 2 πn, u = π + 2 πn

Resolver

u = 0 + 2 πn : u = 2 πn

u = 0 + 2 πn

0 + 2 πn = 2 πn

u = 2 πn

u = 2 πn, u = π + 2 πn

- 2 + 2 cos (u) = 0 : u = \frac{π}{4} + 2 πn, u = \frac{7 π}{4} + 2 πn

- 2 + 2 cos (u) = 0

Mova

2

para o lado direito

- 2 + 2 cos (u) = 0

Adicionar

2

a ambos os lados

- 2 + 2 cos (u) + 2 = 0 + 2

Simplificar

2 cos (u) = 2

2 cos (u) = 2

Dividir ambos os lados por

2

2 cos (u) = 2

Dividir ambos os lados por

2

\frac{2 cos ( u )}{2} = \frac{2}{2}

Simplificar

cos (u) = \frac{2}{2}

cos (u) = \frac{2}{2}

Soluções gerais para

cos (u) = \frac{2}{2}

cos (x)

tabela de periodicidade com ciclo de

2 πn

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

u = \frac{π}{4} + 2 πn, u = \frac{7 π}{4} + 2 πn

u = \frac{π}{4} + 2 πn, u = \frac{7 π}{4} + 2 πn

Combinar toda as soluções

u = 2 πn, u = π + 2 πn, u = \frac{π}{4} + 2 πn, u = \frac{7 π}{4} + 2 πn

Combinar toda as soluções

u = 2 πn, u = π + 2 πn, u = \frac{3 π}{4} + 2 πn, u = \frac{5 π}{4} + 2 πn, u = \frac{π}{4} + 2 πn, u = \frac{7 π}{4} + 2 πn

Substituir na equação

u = \frac{x}{2}

\frac{x}{2} = 2 πn : x = 4 πn

\frac{x}{2} = 2 πn

Multiplicar ambos os lados por

2

\frac{x}{2} = 2 πn

Multiplicar ambos os lados por

2

\frac{2 x}{2} = 2 \cdot 2 πn

Simplificar

x = 4 πn

x = 4 πn

\frac{x}{2} = π + 2 πn : x = 2 π + 4 πn

\frac{x}{2} = π + 2 πn

Multiplicar ambos os lados por

2

\frac{x}{2} = π + 2 πn

Multiplicar ambos os lados por

2

\frac{2 x}{2} = 2 π + 2 \cdot 2 πn

Simplificar

x = 2 π + 4 πn

x = 2 π + 4 πn

\frac{x}{2} = \frac{3 π}{4} + 2 πn : x = \frac{3 π}{2} + 4 πn

\frac{x}{2} = \frac{3 π}{4} + 2 πn

Multiplicar ambos os lados por

2

\frac{x}{2} = \frac{3 π}{4} + 2 πn

Multiplicar ambos os lados por

2

\frac{2 x}{2} = 2 \cdot \frac{3 π}{4} + 2 \cdot 2 πn

Simplificar

\frac{2 x}{2} = 2 \cdot \frac{3 π}{4} + 2 \cdot 2 πn

Simplificar

\frac{2 x}{2} : x

\frac{2 x}{2}

Dividir:

\frac{2}{2} = 1

= x

Simplificar

2 \cdot \frac{3 π}{4} + 2 \cdot 2 πn : \frac{3 π}{2} + 4 πn

2 \cdot \frac{3 π}{4} + 2 \cdot 2 πn

2 \cdot \frac{3 π}{4} = \frac{3 π}{2}

2 \cdot \frac{3 π}{4}

Multiplicar frações:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

= \frac{3 π 2}{4}

Multiplicar os números:

3 \cdot 2 = 6

= \frac{6 π}{4}

Eliminar o fator comum:

2

= \frac{3 π}{2}

2 \cdot 2 πn = 4 πn

2 \cdot 2 πn

Multiplicar os números:

2 \cdot 2 = 4

= 4 πn

= \frac{3 π}{2} + 4 πn

x = \frac{3 π}{2} + 4 πn

x = \frac{3 π}{2} + 4 πn

x = \frac{3 π}{2} + 4 πn

\frac{x}{2} = \frac{5 π}{4} + 2 πn : x = \frac{5 π}{2} + 4 πn

\frac{x}{2} = \frac{5 π}{4} + 2 πn

Multiplicar ambos os lados por

2

\frac{x}{2} = \frac{5 π}{4} + 2 πn

Multiplicar ambos os lados por

2

\frac{2 x}{2} = 2 \cdot \frac{5 π}{4} + 2 \cdot 2 πn

Simplificar

\frac{2 x}{2} = 2 \cdot \frac{5 π}{4} + 2 \cdot 2 πn

Simplificar

\frac{2 x}{2} : x

\frac{2 x}{2}

Dividir:

\frac{2}{2} = 1

= x

Simplificar

2 \cdot \frac{5 π}{4} + 2 \cdot 2 πn : \frac{5 π}{2} + 4 πn

2 \cdot \frac{5 π}{4} + 2 \cdot 2 πn

2 \cdot \frac{5 π}{4} = \frac{5 π}{2}

2 \cdot \frac{5 π}{4}

Multiplicar frações:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

= \frac{5 π 2}{4}

Multiplicar os números:

5 \cdot 2 = 10

= \frac{10 π}{4}

Eliminar o fator comum:

2

= \frac{5 π}{2}

2 \cdot 2 πn = 4 πn

2 \cdot 2 πn

Multiplicar os números:

2 \cdot 2 = 4

= 4 πn

= \frac{5 π}{2} + 4 πn

x = \frac{5 π}{2} + 4 πn

x = \frac{5 π}{2} + 4 πn

x = \frac{5 π}{2} + 4 πn

\frac{x}{2} = \frac{π}{4} + 2 πn : x = \frac{π}{2} + 4 πn

\frac{x}{2} = \frac{π}{4} + 2 πn

Multiplicar ambos os lados por

2

\frac{x}{2} = \frac{π}{4} + 2 πn

Multiplicar ambos os lados por

2

\frac{2 x}{2} = 2 \cdot \frac{π}{4} + 2 \cdot 2 πn

Simplificar

\frac{2 x}{2} = 2 \cdot \frac{π}{4} + 2 \cdot 2 πn

Simplificar

\frac{2 x}{2} : x

\frac{2 x}{2}

Dividir:

\frac{2}{2} = 1

= x

Simplificar

2 \cdot \frac{π}{4} + 2 \cdot 2 πn : \frac{π}{2} + 4 πn

2 \cdot \frac{π}{4} + 2 \cdot 2 πn

2 \cdot \frac{π}{4} = \frac{π}{2}

2 \cdot \frac{π}{4}

Multiplicar frações:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

= \frac{π 2}{4}

Eliminar o fator comum:

2

= \frac{π}{2}

2 \cdot 2 πn = 4 πn

2 \cdot 2 πn

Multiplicar os números:

2 \cdot 2 = 4

= 4 πn

= \frac{π}{2} + 4 πn

x = \frac{π}{2} + 4 πn

x = \frac{π}{2} + 4 πn

x = \frac{π}{2} + 4 πn

\frac{x}{2} = \frac{7 π}{4} + 2 πn : x = \frac{7 π}{2} + 4 πn

\frac{x}{2} = \frac{7 π}{4} + 2 πn

Multiplicar ambos os lados por

2

\frac{x}{2} = \frac{7 π}{4} + 2 πn

Multiplicar ambos os lados por

2

\frac{2 x}{2} = 2 \cdot \frac{7 π}{4} + 2 \cdot 2 πn

Simplificar

\frac{2 x}{2} = 2 \cdot \frac{7 π}{4} + 2 \cdot 2 πn

Simplificar

\frac{2 x}{2} : x

\frac{2 x}{2}

Dividir:

\frac{2}{2} = 1

= x

Simplificar

2 \cdot \frac{7 π}{4} + 2 \cdot 2 πn : \frac{7 π}{2} + 4 πn

2 \cdot \frac{7 π}{4} + 2 \cdot 2 πn

2 \cdot \frac{7 π}{4} = \frac{7 π}{2}

2 \cdot \frac{7 π}{4}

Multiplicar frações:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

= \frac{7 π 2}{4}

Multiplicar os números:

7 \cdot 2 = 14

= \frac{14 π}{4}

Eliminar o fator comum:

2

= \frac{7 π}{2}

2 \cdot 2 πn = 4 πn

2 \cdot 2 πn

Multiplicar os números:

2 \cdot 2 = 4

= 4 πn

= \frac{7 π}{2} + 4 πn

x = \frac{7 π}{2} + 4 πn

x = \frac{7 π}{2} + 4 πn

x = \frac{7 π}{2} + 4 πn

x = 4 πn, x = 2 π + 4 πn, x = \frac{3 π}{2} + 4 πn, x = \frac{5 π}{2} + 4 πn, x = \frac{π}{2} + 4 πn, x = \frac{7 π}{2} + 4 πn

Gráfico

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