Given the inequality:
$$\sin{\left(\frac{x}{4} \right)} < \frac{2}{\sqrt{3}}$$
To solve this inequality, we must first solve the corresponding equation:
$$\sin{\left(\frac{x}{4} \right)} = \frac{2}{\sqrt{3}}$$
Solve:
Given the equation
$$\sin{\left(\frac{x}{4} \right)} = \frac{2}{\sqrt{3}}$$
- this is the simplest trigonometric equation
As right part of the equation
modulo =
True
but sin
can no be more than 1 or less than -1
so the solution of the equation d'not exist.
$$x_{1} = 4 \pi - 4 \operatorname{asin}{\left(\frac{2 \sqrt{3}}{3} \right)}$$
$$x_{2} = 4 \operatorname{asin}{\left(\frac{2 \sqrt{3}}{3} \right)}$$
Exclude the complex solutions:
This equation has no roots,
this inequality is executed for any x value or has no solutions
check it
subtitute random point x, for example
x0 = 0
$$\sin{\left(\frac{0}{4} \right)} < \frac{2}{\sqrt{3}}$$
___
2*\/ 3
0 < -------
3
so the inequality is always executed