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sinx>-sqrt2/2 inequation

A inequation with variable

The solution

You have entered [src]
            ___ 
         -\/ 2  
sin(x) > -------
            2   
$$\sin{\left(x \right)} > \frac{\left(-1\right) \sqrt{2}}{2}$$
sin(x) > (-sqrt(2))/2
Detail solution
Given the inequality:
$$\sin{\left(x \right)} > \frac{\left(-1\right) \sqrt{2}}{2}$$
To solve this inequality, we must first solve the corresponding equation:
$$\sin{\left(x \right)} = \frac{\left(-1\right) \sqrt{2}}{2}$$
Solve:
Given the equation
$$\sin{\left(x \right)} = \frac{\left(-1\right) \sqrt{2}}{2}$$
- this is the simplest trigonometric equation
This equation is transformed to
$$x = 2 \pi n + \operatorname{asin}{\left(- \frac{\sqrt{2}}{2} \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(- \frac{\sqrt{2}}{2} \right)} + \pi$$
Or
$$x = 2 \pi n - \frac{\pi}{4}$$
$$x = 2 \pi n + \frac{5 \pi}{4}$$
, where n - is a integer
$$x_{1} = 2 \pi n - \frac{\pi}{4}$$
$$x_{2} = 2 \pi n + \frac{5 \pi}{4}$$
$$x_{1} = 2 \pi n - \frac{\pi}{4}$$
$$x_{2} = 2 \pi n + \frac{5 \pi}{4}$$
This roots
$$x_{1} = 2 \pi n - \frac{\pi}{4}$$
$$x_{2} = 2 \pi n + \frac{5 \pi}{4}$$
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
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$\left(2 \pi n - \frac{\pi}{4}\right) + - \frac{1}{10}$$
=
$$2 \pi n - \frac{\pi}{4} - \frac{1}{10}$$
substitute to the expression
$$\sin{\left(x \right)} > \frac{\left(-1\right) \sqrt{2}}{2}$$
$$\sin{\left(2 \pi n - \frac{\pi}{4} - \frac{1}{10} \right)} > \frac{\left(-1\right) \sqrt{2}}{2}$$
                            ___ 
    /1    pi         \   -\/ 2  
-sin|-- + -- - 2*pi*n| > -------
    \10   4          /      2   
                         

Then
$$x < 2 \pi n - \frac{\pi}{4}$$
no execute
one of the solutions of our inequality is:
$$x > 2 \pi n - \frac{\pi}{4} \wedge x < 2 \pi n + \frac{5 \pi}{4}$$
         _____  
        /     \  
-------ο-------ο-------
       x1      x2
Solving inequality on a graph
Rapid solution [src]
  /   /            5*pi\     /           7*pi    \\
Or|And|0 <= x, x < ----|, And|x <= 2*pi, ---- < x||
  \   \             4  /     \            4      //
$$\left(0 \leq x \wedge x < \frac{5 \pi}{4}\right) \vee \left(x \leq 2 \pi \wedge \frac{7 \pi}{4} < x\right)$$
((0 <= x)∧(x < 5*pi/4))∨((x <= 2*pi)∧(7*pi/4 < x))
Rapid solution 2 [src]
    5*pi     7*pi       
[0, ----) U (----, 2*pi]
     4        4         
$$x\ in\ \left[0, \frac{5 \pi}{4}\right) \cup \left(\frac{7 \pi}{4}, 2 \pi\right]$$
x in Union(Interval.Ropen(0, 5*pi/4), Interval.Lopen(7*pi/4, 2*pi))