Sr Examen

sinx+3cosx>2 desigualdades

En la desigualdad la incógnita

Solución

Ha introducido [src]
sin(x) + 3*cos(x) > 2
sin(x)+3cos(x)>2\sin{\left(x \right)} + 3 \cos{\left(x \right)} > 2
sin(x) + 3*cos(x) > 2
Solución detallada
Se da la desigualdad:
sin(x)+3cos(x)>2\sin{\left(x \right)} + 3 \cos{\left(x \right)} > 2
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
sin(x)+3cos(x)=2\sin{\left(x \right)} + 3 \cos{\left(x \right)} = 2
Resolvemos:
x1=2atan(1565)x_{1} = 2 \operatorname{atan}{\left(\frac{1}{5} - \frac{\sqrt{6}}{5} \right)}
x2=2atan(15+65)x_{2} = 2 \operatorname{atan}{\left(\frac{1}{5} + \frac{\sqrt{6}}{5} \right)}
x1=2atan(1565)x_{1} = 2 \operatorname{atan}{\left(\frac{1}{5} - \frac{\sqrt{6}}{5} \right)}
x2=2atan(15+65)x_{2} = 2 \operatorname{atan}{\left(\frac{1}{5} + \frac{\sqrt{6}}{5} \right)}
Las raíces dadas
x1=2atan(1565)x_{1} = 2 \operatorname{atan}{\left(\frac{1}{5} - \frac{\sqrt{6}}{5} \right)}
x2=2atan(15+65)x_{2} = 2 \operatorname{atan}{\left(\frac{1}{5} + \frac{\sqrt{6}}{5} \right)}
son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
x0<x1x_{0} < x_{1}
Consideremos, por ejemplo, el punto
x0=x1110x_{0} = x_{1} - \frac{1}{10}
=
2atan(1565)1102 \operatorname{atan}{\left(\frac{1}{5} - \frac{\sqrt{6}}{5} \right)} - \frac{1}{10}
=
2atan(1565)1102 \operatorname{atan}{\left(\frac{1}{5} - \frac{\sqrt{6}}{5} \right)} - \frac{1}{10}
lo sustituimos en la expresión
sin(x)+3cos(x)>2\sin{\left(x \right)} + 3 \cos{\left(x \right)} > 2
sin(2atan(1565)110)+3cos(2atan(1565)110)>2\sin{\left(2 \operatorname{atan}{\left(\frac{1}{5} - \frac{\sqrt{6}}{5} \right)} - \frac{1}{10} \right)} + 3 \cos{\left(2 \operatorname{atan}{\left(\frac{1}{5} - \frac{\sqrt{6}}{5} \right)} - \frac{1}{10} \right)} > 2
     /             /      ___\\      /             /      ___\\    
     |  1          |1   \/ 6 ||      |  1          |1   \/ 6 ||    
3*cos|- -- + 2*atan|- - -----|| + sin|- -- + 2*atan|- - -----|| > 2
     \  10         \5     5  //      \  10         \5     5  //    
    

Entonces
x<2atan(1565)x < 2 \operatorname{atan}{\left(\frac{1}{5} - \frac{\sqrt{6}}{5} \right)}
no se cumple
significa que una de las soluciones de nuestra ecuación será con:
x>2atan(1565)x<2atan(15+65)x > 2 \operatorname{atan}{\left(\frac{1}{5} - \frac{\sqrt{6}}{5} \right)} \wedge x < 2 \operatorname{atan}{\left(\frac{1}{5} + \frac{\sqrt{6}}{5} \right)}
         _____  
        /     \  
-------ο-------ο-------
       x1      x2
Solución de la desigualdad en el gráfico
05-15-10-510155-5
Respuesta rápida [src]
  /   /                /        ___\\     /                      /        ___\    \\
  |   |                |2 + 3*\/ 6 ||     |                      |2 - 3*\/ 6 |    ||
Or|And|0 <= x, x < atan|-----------||, And|x <= 2*pi, 2*pi + atan|-----------| < x||
  |   |                |       ___ ||     |                      |       ___ |    ||
  \   \                \ 6 - \/ 6  //     \                      \ 6 + \/ 6  /    //
(0xx<atan(2+3666))(x2πatan(2366+6)+2π<x)\left(0 \leq x \wedge x < \operatorname{atan}{\left(\frac{2 + 3 \sqrt{6}}{6 - \sqrt{6}} \right)}\right) \vee \left(x \leq 2 \pi \wedge \operatorname{atan}{\left(\frac{2 - 3 \sqrt{6}}{\sqrt{6} + 6} \right)} + 2 \pi < x\right)
((0 <= x)∧(x < atan((2 + 3*sqrt(6))/(6 - sqrt(6)))))∨((x <= 2*pi)∧(2*pi + atan((2 - 3*sqrt(6))/(6 + sqrt(6))) < x))
Respuesta rápida 2 [src]
        /        ___\                /        ___\       
        |2 + 3*\/ 6 |                |2 - 3*\/ 6 |       
[0, atan|-----------|) U (2*pi + atan|-----------|, 2*pi]
        |       ___ |                |       ___ |       
        \ 6 - \/ 6  /                \ 6 + \/ 6  /       
x in [0,atan(2+3666))(atan(2366+6)+2π,2π]x\ in\ \left[0, \operatorname{atan}{\left(\frac{2 + 3 \sqrt{6}}{6 - \sqrt{6}} \right)}\right) \cup \left(\operatorname{atan}{\left(\frac{2 - 3 \sqrt{6}}{\sqrt{6} + 6} \right)} + 2 \pi, 2 \pi\right]
x in Union(Interval.Ropen(0, atan((2 + 3*sqrt(6))/(6 - sqrt(6)))), Interval.Lopen(atan((2 - 3*sqrt(6))/(sqrt(6) + 6)) + 2*pi, 2*pi))