Mister Exam

sinx>-0.5 inequation

A inequation with variable

The solution

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sin(x) > -1/2
$$\sin{\left(x \right)} > - \frac{1}{2}$$
sin(x) > -1/2
Detail solution
Given the inequality:
$$\sin{\left(x \right)} > - \frac{1}{2}$$
To solve this inequality, we must first solve the corresponding equation:
$$\sin{\left(x \right)} = - \frac{1}{2}$$
Solve:
Given the equation
$$\sin{\left(x \right)} = - \frac{1}{2}$$
- this is the simplest trigonometric equation
This equation is transformed to
$$x = 2 \pi n + \operatorname{asin}{\left(- \frac{1}{2} \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(- \frac{1}{2} \right)} + \pi$$
Or
$$x = 2 \pi n - \frac{\pi}{6}$$
$$x = 2 \pi n + \frac{7 \pi}{6}$$
, where n - is a integer
$$x_{1} = 2 \pi n - \frac{\pi}{6}$$
$$x_{2} = 2 \pi n + \frac{7 \pi}{6}$$
$$x_{1} = 2 \pi n - \frac{\pi}{6}$$
$$x_{2} = 2 \pi n + \frac{7 \pi}{6}$$
This roots
$$x_{1} = 2 \pi n - \frac{\pi}{6}$$
$$x_{2} = 2 \pi n + \frac{7 \pi}{6}$$
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
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$\left(2 \pi n - \frac{\pi}{6}\right) + - \frac{1}{10}$$
=
$$2 \pi n - \frac{\pi}{6} - \frac{1}{10}$$
substitute to the expression
$$\sin{\left(x \right)} > - \frac{1}{2}$$
$$\sin{\left(2 \pi n - \frac{\pi}{6} - \frac{1}{10} \right)} > - \frac{1}{2}$$
    /1    pi         \       
-sin|-- + -- - 2*pi*n| > -1/2
    \10   6          /       

Then
$$x < 2 \pi n - \frac{\pi}{6}$$
no execute
one of the solutions of our inequality is:
$$x > 2 \pi n - \frac{\pi}{6} \wedge x < 2 \pi n + \frac{7 \pi}{6}$$
         _____  
        /     \  
-------ο-------ο-------
       x1      x2
Solving inequality on a graph
Rapid solution [src]
  /   /            7*pi\     /           11*pi    \\
Or|And|0 <= x, x < ----|, And|x <= 2*pi, ----- < x||
  \   \             6  /     \             6      //
$$\left(0 \leq x \wedge x < \frac{7 \pi}{6}\right) \vee \left(x \leq 2 \pi \wedge \frac{11 \pi}{6} < x\right)$$
((0 <= x)∧(x < 7*pi/6))∨((x <= 2*pi)∧(11*pi/6 < x))
Rapid solution 2 [src]
    7*pi     11*pi       
[0, ----) U (-----, 2*pi]
     6         6         
$$x\ in\ \left[0, \frac{7 \pi}{6}\right) \cup \left(\frac{11 \pi}{6}, 2 \pi\right]$$
x in Union(Interval.Ropen(0, 7*pi/6), Interval.Lopen(11*pi/6, 2*pi))