Solución detallada
Tenemos la ecuación
$$\frac{a}{5} \cos{\left(\frac{a x}{5} \right)} + \sin{\left(\frac{a x}{5} \right)} = 0$$
cambiamos:
$$\frac{\sin{\left(\frac{a x}{5} \right)}}{\cos{\left(\frac{a x}{5} \right)}} = - \frac{a}{5}$$
o
$$\tan{\left(\frac{a x}{5} \right)} = - \frac{a}{5}$$
es la ecuación trigonométrica más simple
Esta ecuación se reorganiza en
$$\frac{a x}{5} = \pi n + \operatorname{atan}{\left(\frac{a}{5} \right)}$$
O
$$\frac{a x}{5} = \pi n + \operatorname{atan}{\left(\frac{a}{5} \right)}$$
, donde n es cualquier número entero
Dividamos ambos miembros de la ecuación obtenida en
$$\frac{a}{5}$$
obtenemos la respuesta:
$$x_{1} = \frac{5 \left(\pi n + \operatorname{atan}{\left(\frac{a}{5} \right)}\right)}{a}$$
Suma y producto de raíces
[src]
/ / _________\\ / / _________\\ / / _________\\ / / _________\\
| | / 2 || | | / 2 || | | / 2 || | | / 2 ||
| |-5 + \/ 25 + a || | |-5 + \/ 25 + a || | |5 + \/ 25 + a || | |5 + \/ 25 + a ||
|atan|-----------------|| |atan|-----------------|| |atan|----------------|| |atan|----------------||
| \ a /| | \ a /| | \ a /| | \ a /|
- 10*re|-----------------------| - 10*I*im|-----------------------| + 10*re|----------------------| + 10*I*im|----------------------|
\ a / \ a / \ a / \ a /
$$\left(- 10 \operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)} - 10 i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)}\right) + \left(10 \operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)} + 10 i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)}\right)$$
/ / _________\\ / / _________\\ / / _________\\ / / _________\\
| | / 2 || | | / 2 || | | / 2 || | | / 2 ||
| |-5 + \/ 25 + a || | |5 + \/ 25 + a || | |-5 + \/ 25 + a || | |5 + \/ 25 + a ||
|atan|-----------------|| |atan|----------------|| |atan|-----------------|| |atan|----------------||
| \ a /| | \ a /| | \ a /| | \ a /|
- 10*re|-----------------------| + 10*re|----------------------| - 10*I*im|-----------------------| + 10*I*im|----------------------|
\ a / \ a / \ a / \ a /
$$- 10 \operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)} + 10 \operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)} - 10 i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)} + 10 i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)}$$
/ / / _________\\ / / _________\\\ / / / _________\\ / / _________\\\
| | | / 2 || | | / 2 ||| | | | / 2 || | | / 2 |||
| | |-5 + \/ 25 + a || | |-5 + \/ 25 + a ||| | | |5 + \/ 25 + a || | |5 + \/ 25 + a |||
| |atan|-----------------|| |atan|-----------------||| | |atan|----------------|| |atan|----------------|||
| | \ a /| | \ a /|| | | \ a /| | \ a /||
|- 10*re|-----------------------| - 10*I*im|-----------------------||*|10*re|----------------------| + 10*I*im|----------------------||
\ \ a / \ a // \ \ a / \ a //
$$\left(- 10 \operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)} - 10 i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)}\right) \left(10 \operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)} + 10 i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)}\right)$$
/ / / _________\\ / / _________\\\ / / / _________\\ / / _________\\\
| | | / 2 || | | / 2 ||| | | | / 2 || | | / 2 |||
| | |-5 + \/ 25 + a || | |-5 + \/ 25 + a ||| | | |5 + \/ 25 + a || | |5 + \/ 25 + a |||
| |atan|-----------------|| |atan|-----------------||| | |atan|----------------|| |atan|----------------|||
| | \ a /| | \ a /|| | | \ a /| | \ a /||
-100*|I*im|-----------------------| + re|-----------------------||*|I*im|----------------------| + re|----------------------||
\ \ a / \ a // \ \ a / \ a //
$$- 100 \left(\operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)} + i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)}\right) \left(\operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)} + i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)}\right)$$
-100*(i*im(atan((-5 + sqrt(25 + a^2))/a)/a) + re(atan((-5 + sqrt(25 + a^2))/a)/a))*(i*im(atan((5 + sqrt(25 + a^2))/a)/a) + re(atan((5 + sqrt(25 + a^2))/a)/a))
/ / _________\\ / / _________\\
| | / 2 || | | / 2 ||
| |-5 + \/ 25 + a || | |-5 + \/ 25 + a ||
|atan|-----------------|| |atan|-----------------||
| \ a /| | \ a /|
x1 = - 10*re|-----------------------| - 10*I*im|-----------------------|
\ a / \ a /
$$x_{1} = - 10 \operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)} - 10 i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} - 5}{a} \right)}}{a}\right)}$$
/ / _________\\ / / _________\\
| | / 2 || | | / 2 ||
| |5 + \/ 25 + a || | |5 + \/ 25 + a ||
|atan|----------------|| |atan|----------------||
| \ a /| | \ a /|
x2 = 10*re|----------------------| + 10*I*im|----------------------|
\ a / \ a /
$$x_{2} = 10 \operatorname{re}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)} + 10 i \operatorname{im}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{a^{2} + 25} + 5}{a} \right)}}{a}\right)}$$
x2 = 10*re(atan((sqrt(a^2 + 25) + 5)/a)/a) + 10*i*im(atan((sqrt(a^2 + 25) + 5)/a)/a)