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Popular Trigonometría >

(sec^2(x))/2 =2cos^2(x)

Solución

\frac{sec ^{2} ( x )}{2} = 2 cos^{2} (x)

Solución

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

Grados

x = 4 5^{\circ} + 36 0^{\circ} n, x = 31 5^{\circ} + 36 0^{\circ} n, x = 13 5^{\circ} + 36 0^{\circ} n, x = 22 5^{\circ} + 36 0^{\circ} n

Pasos de solución

\frac{sec ^{2} ( x )}{2} = 2 cos^{2} (x)

Restar

2 cos^{2} (x)

de ambos lados

\frac{sec ^{2} ( x )}{2} - 2 cos^{2} (x) = 0

Simplificar

\frac{sec ^{2} ( x )}{2} - 2 cos^{2} (x) : \frac{sec ^{2} ( x ) - 4 cos ^{2} ( x )}{2}

\frac{sec ^{2} ( x )}{2} - 2 cos^{2} (x)

Convertir a fracción:

2 cos^{2} (x) = \frac{2 cos ^{2} ( x ) 2}{2}

= \frac{sec ^{2} ( x )}{2} - \frac{2 cos ^{2} ( x ) \cdot 2}{2}

Ya que los denominadores son iguales, combinar las fracciones:

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

= \frac{sec ^{2} ( x ) - 2 cos ^{2} ( x ) \cdot 2}{2}

Multiplicar los numeros:

2 \cdot 2 = 4

= \frac{sec ^{2} ( x ) - 4 cos ^{2} ( x )}{2}

\frac{sec ^{2} ( x ) - 4 cos ^{2} ( x )}{2} = 0

\frac{f ( x )}{g ( x )} = 0 \Rightarrow f (x) = 0

sec^{2} (x) - 4 cos^{2} (x) = 0

Factorizar

sec^{2} (x) - 4 cos^{2} (x) : (sec (x) + 2 cos (x)) (sec (x) - 2 cos (x))

sec^{2} (x) - 4 cos^{2} (x)

Reescribir

sec^{2} (x) - 4 cos^{2} (x)

como

sec^{2} (x) - (2 cos (x))^{2}

sec^{2} (x) - 4 cos^{2} (x)

Reescribir

4

como

2^{2}

= sec^{2} (x) - 2^{2} cos^{2} (x)

Aplicar las leyes de los exponentes:

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

2^{2} cos^{2} (x) = (2 cos (x))^{2}

= sec^{2} (x) - (2 cos (x))^{2}

= sec^{2} (x) - (2 cos (x))^{2}

Aplicar la siguiente regla para binomios al cuadrado:

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

sec^{2} (x) - (2 cos (x))^{2} = (sec (x) + 2 cos (x)) (sec (x) - 2 cos (x))

= (sec (x) + 2 cos (x)) (sec (x) - 2 cos (x))

(sec (x) + 2 cos (x)) (sec (x) - 2 cos (x)) = 0

Resolver cada parte por separado

sec (x) + 2 cos (x) = 0 or sec (x) - 2 cos (x) = 0

sec (x) + 2 cos (x) = 0 :

Sin solución

sec (x) + 2 cos (x) = 0

Re-escribir usando identidades trigonométricas

sec (x) + 2 cos (x)

Utilizar la identidad trigonométrica básica:

cos (x) = \frac{1}{sec ( x )}

= sec (x) + 2 \cdot \frac{1}{sec ( x )}

2 \cdot \frac{1}{sec ( x )} = \frac{2}{sec ( x )}

2 \cdot \frac{1}{sec ( x )}

Multiplicar fracciones:

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

= \frac{1 \cdot 2}{sec ( x )}

Multiplicar los numeros:

1 \cdot 2 = 2

= \frac{2}{sec ( x )}

= sec (x) + \frac{2}{sec ( x )}

\frac{2}{sec ( x )} + sec (x) = 0

Usando el método de sustitución

\frac{2}{sec ( x )} + sec (x) = 0

Sea:

sec (x) = u

\frac{2}{u} + u = 0

\frac{2}{u} + u = 0 : u = 2 i, u = - 2 i

\frac{2}{u} + u = 0

Multiplicar ambos lados por

u

\frac{2}{u} + u = 0

Multiplicar ambos lados por

u

\frac{2}{u} u + uu = 0 \cdot u

Simplificar

\frac{2}{u} u + uu = 0 \cdot u

Simplificar

\frac{2}{u} u : 2

\frac{2}{u} u

Multiplicar fracciones:

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

= \frac{2 u}{u}

Eliminar los terminos comunes:

u

= 2

Simplificar

uu : u^{2}

uu

Aplicar las leyes de los exponentes:

a^{b} \cdot a^{c} = a^{b + c}

uu = u^{1 + 1}

= u^{1 + 1}

Sumar:

1 + 1 = 2

= u^{2}

Simplificar

0 \cdot u : 0

0 \cdot u

Aplicar la regla

0 \cdot a = 0

= 0

2 + u^{2} = 0

2 + u^{2} = 0

2 + u^{2} = 0

Resolver

2 + u^{2} = 0 : u = 2 i, u = - 2 i

2 + u^{2} = 0

Desplace

2

a la derecha

2 + u^{2} = 0

Restar

2

de ambos lados

2 + u^{2} - 2 = 0 - 2

Simplificar

u^{2} = - 2

u^{2} = - 2

Para

x^{2} = f (a)

las soluciones son

x = f (a), - f (a)

u = - 2, u = - - 2

Simplificar

- 2 : 2 i

- 2

Aplicar las leyes de los exponentes:

- a = - 1 a

- 2 = - 1 2

= - 1 2

Aplicar las propiedades de los numeros imaginarios:

- 1 = i

= 2 i

Simplificar

- - 2 : - 2 i

- - 2

Simplificar

- 2 : 2 i

- 2

Aplicar las leyes de los exponentes:

- a = - 1 a

- 2 = - 1 2

= - 1 2

Aplicar las propiedades de los numeros imaginarios:

- 1 = i

= 2 i

= - 2 i

u = 2 i, u = - 2 i

u = 2 i, u = - 2 i

Sustituir en la ecuación

u = sec (x)

sec (x) = 2 i, sec (x) = - 2 i

sec (x) = 2 i, sec (x) = - 2 i

sec (x) = 2 i :

Sin solución

sec (x) = 2 i

Sin soluci \overset{o}{ˊ} n

sec (x) = - 2 i :

Sin solución

sec (x) = - 2 i

Sin soluci \overset{o}{ˊ} n

Combinar toda las soluciones

Sin soluci \overset{o}{ˊ} n

sec (x) - 2 cos (x) = 0 : x = \frac{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn, x = \frac{3 π}{4} + 2 πn, x = \frac{5 π}{4} + 2 πn

sec (x) - 2 cos (x) = 0

Re-escribir usando identidades trigonométricas

sec (x) - 2 cos (x)

Utilizar la identidad trigonométrica básica:

cos (x) = \frac{1}{sec ( x )}

= sec (x) - 2 \cdot \frac{1}{sec ( x )}

2 \cdot \frac{1}{sec ( x )} = \frac{2}{sec ( x )}

2 \cdot \frac{1}{sec ( x )}

Multiplicar fracciones:

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

= \frac{1 \cdot 2}{sec ( x )}

Multiplicar los numeros:

1 \cdot 2 = 2

= \frac{2}{sec ( x )}

= sec (x) - \frac{2}{sec ( x )}

- \frac{2}{sec ( x )} + sec (x) = 0

Usando el método de sustitución

- \frac{2}{sec ( x )} + sec (x) = 0

Sea:

sec (x) = u

- \frac{2}{u} + u = 0

- \frac{2}{u} + u = 0 : u = 2, u = - 2

- \frac{2}{u} + u = 0

Multiplicar ambos lados por

u

- \frac{2}{u} + u = 0

Multiplicar ambos lados por

u

- \frac{2}{u} u + uu = 0 \cdot u

Simplificar

- \frac{2}{u} u + uu = 0 \cdot u

Simplificar

- \frac{2}{u} u : - 2

- \frac{2}{u} u

Multiplicar fracciones:

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

= - \frac{2 u}{u}

Eliminar los terminos comunes:

u

= - 2

Simplificar

uu : u^{2}

uu

Aplicar las leyes de los exponentes:

a^{b} \cdot a^{c} = a^{b + c}

uu = u^{1 + 1}

= u^{1 + 1}

Sumar:

1 + 1 = 2

= u^{2}

Simplificar

0 \cdot u : 0

0 \cdot u

Aplicar la regla

0 \cdot a = 0

= 0

- 2 + u^{2} = 0

- 2 + u^{2} = 0

- 2 + u^{2} = 0

Resolver

- 2 + u^{2} = 0 : u = 2, u = - 2

- 2 + u^{2} = 0

Desplace

2

a la derecha

- 2 + u^{2} = 0

Sumar

2

a ambos lados

- 2 + u^{2} + 2 = 0 + 2

Simplificar

u^{2} = 2

u^{2} = 2

Para

x^{2} = f (a)

las soluciones son

x = f (a), - f (a)

u = 2, u = - 2

u = 2, u = - 2

Verificar las soluciones

Encontrar los puntos no definidos (singularidades):

u = 0

Tomar el(los) denominador(es) de

- \frac{2}{u} + u

y comparar con cero

u = 0

Los siguientes puntos no están definidos

u = 0

Combinar los puntos no definidos con las soluciones:

u = 2, u = - 2

Sustituir en la ecuación

u = sec (x)

sec (x) = 2, sec (x) = - 2

sec (x) = 2, sec (x) = - 2

sec (x) = 2 : x = \frac{π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

sec (x) = 2

Soluciones generales para

sec (x) = 2

sec (x)

tabla de valores periódicos con

2 πn

intervalos:

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} sec (x) 1 \frac{2 3}{3} 22 Undefined - 2 - 2 - \frac{2 3}{3} 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} sec (x) - 1 - \frac{2 3}{3} - 2 - 2 Undefined 22 \frac{2 3}{3}

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

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

sec (x) = - 2 : x = \frac{3 π}{4} + 2 πn, x = \frac{5 π}{4} + 2 πn

sec (x) = - 2

Soluciones generales para

sec (x) = - 2

sec (x)

tabla de valores periódicos con

2 πn

intervalos:

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} sec (x) 1 \frac{2 3}{3} 22 Undefined - 2 - 2 - \frac{2 3}{3} 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} sec (x) - 1 - \frac{2 3}{3} - 2 - 2 Undefined 22 \frac{2 3}{3}

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

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

Combinar toda las soluciones

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

Combinar toda las soluciones

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

Gráfica

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