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sin(3*x+1)>0 inequation

A inequation with variable

The solution

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sin(3*x + 1) > 0
$$\sin{\left(3 x + 1 \right)} > 0$$
sin(3*x + 1) > 0
Detail solution
Given the inequality:
$$\sin{\left(3 x + 1 \right)} > 0$$
To solve this inequality, we must first solve the corresponding equation:
$$\sin{\left(3 x + 1 \right)} = 0$$
Solve:
Given the equation
$$\sin{\left(3 x + 1 \right)} = 0$$
- this is the simplest trigonometric equation
with the change of sign in 0

We get:
$$\sin{\left(3 x + 1 \right)} = 0$$
This equation is transformed to
$$3 x + 1 = 2 \pi n + \operatorname{asin}{\left(0 \right)}$$
$$3 x + 1 = 2 \pi n - \operatorname{asin}{\left(0 \right)} + \pi$$
Or
$$3 x + 1 = 2 \pi n$$
$$3 x + 1 = 2 \pi n + \pi$$
, where n - is a integer
Move
$$1$$
to right part of the equation
with the opposite sign, in total:
$$3 x = 2 \pi n - 1$$
$$3 x = 2 \pi n - 1 + \pi$$
Divide both parts of the equation by
$$3$$
$$x_{1} = \frac{2 \pi n}{3} - \frac{1}{3}$$
$$x_{2} = \frac{2 \pi n}{3} - \frac{1}{3} + \frac{\pi}{3}$$
$$x_{1} = \frac{2 \pi n}{3} - \frac{1}{3}$$
$$x_{2} = \frac{2 \pi n}{3} - \frac{1}{3} + \frac{\pi}{3}$$
This roots
$$x_{1} = \frac{2 \pi n}{3} - \frac{1}{3}$$
$$x_{2} = \frac{2 \pi n}{3} - \frac{1}{3} + \frac{\pi}{3}$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} < x_{1}$$
For example, let's take the point
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$\left(\frac{2 \pi n}{3} - \frac{1}{3}\right) + - \frac{1}{10}$$
=
$$\frac{2 \pi n}{3} - \frac{13}{30}$$
substitute to the expression
$$\sin{\left(3 x + 1 \right)} > 0$$
$$\sin{\left(3 \left(\frac{2 \pi n}{3} - \frac{13}{30}\right) + 1 \right)} > 0$$
sin(-3/10 + 2*pi*n) > 0

Then
$$x < \frac{2 \pi n}{3} - \frac{1}{3}$$
no execute
one of the solutions of our inequality is:
$$x > \frac{2 \pi n}{3} - \frac{1}{3} \wedge x < \frac{2 \pi n}{3} - \frac{1}{3} + \frac{\pi}{3}$$
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       x1      x2
Solving inequality on a graph
Rapid solution [src]
  /   /               /      /              ___         \      /   _______________________\\\     /              /  /         /  ___                     \\      /   _______________________\\    \\
  |   |               |      |-sin(1/3) + \/ 3 *cos(1/3)|      |  /    2           2      |||     |     2*pi     |  |         |\/ 3 *cos(1/3) + sin(1/3) ||      |  /    2           2      ||    ||
Or|And|0 <= x, x < -I*|I*atan|--------------------------| + log\\/  cos (1/3) + sin (1/3) /||, And|x <= ----, -I*|I*|pi + atan|--------------------------|| + log\\/  cos (1/3) + sin (1/3) /| < x||
  |   |               |      |  ___                     |                                  ||     |      3       |  |         |              ___         ||                                  |    ||
  \   \               \      \\/ 3 *sin(1/3) + cos(1/3) /                                  //     \              \  \         \-cos(1/3) + \/ 3 *sin(1/3)//                                  /    //
$$\left(0 \leq x \wedge x < - i \left(\log{\left(\sqrt{\sin^{2}{\left(\frac{1}{3} \right)} + \cos^{2}{\left(\frac{1}{3} \right)}} \right)} + i \operatorname{atan}{\left(\frac{- \sin{\left(\frac{1}{3} \right)} + \sqrt{3} \cos{\left(\frac{1}{3} \right)}}{\sqrt{3} \sin{\left(\frac{1}{3} \right)} + \cos{\left(\frac{1}{3} \right)}} \right)}\right)\right) \vee \left(x \leq \frac{2 \pi}{3} \wedge - i \left(\log{\left(\sqrt{\sin^{2}{\left(\frac{1}{3} \right)} + \cos^{2}{\left(\frac{1}{3} \right)}} \right)} + i \left(\operatorname{atan}{\left(\frac{\sin{\left(\frac{1}{3} \right)} + \sqrt{3} \cos{\left(\frac{1}{3} \right)}}{- \cos{\left(\frac{1}{3} \right)} + \sqrt{3} \sin{\left(\frac{1}{3} \right)}} \right)} + \pi\right)\right) < x\right)$$
((0 <= x)∧(x < -i*(i*atan((-sin(1/3) + sqrt(3)*cos(1/3))/(sqrt(3)*sin(1/3) + cos(1/3))) + log(sqrt(cos(1/3)^2 + sin(1/3)^2)))))∨((x <= 2*pi/3)∧(-i*(i*(pi + atan((sqrt(3)*cos(1/3) + sin(1/3))/(-cos(1/3) + sqrt(3)*sin(1/3)))) + log(sqrt(cos(1/3)^2 + sin(1/3)^2))) < x))