Mister Exam

tg(2x)<=1 inequation

A inequation with variable

The solution

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tan(2*x) <= 1
$$\tan{\left(2 x \right)} \leq 1$$
tan(2*x) <= 1
Detail solution
Given the inequality:
$$\tan{\left(2 x \right)} \leq 1$$
To solve this inequality, we must first solve the corresponding equation:
$$\tan{\left(2 x \right)} = 1$$
Solve:
Given the equation
$$\tan{\left(2 x \right)} = 1$$
- this is the simplest trigonometric equation
This equation is transformed to
$$2 x = \pi n + \operatorname{atan}{\left(1 \right)}$$
Or
$$2 x = \pi n + \frac{\pi}{4}$$
, where n - is a integer
Divide both parts of the equation by
$$2$$
$$x_{1} = \frac{\pi n}{2} + \frac{\pi}{8}$$
$$x_{1} = \frac{\pi n}{2} + \frac{\pi}{8}$$
This roots
$$x_{1} = \frac{\pi n}{2} + \frac{\pi}{8}$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} \leq x_{1}$$
For example, let's take the point
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$\left(\frac{\pi n}{2} + \frac{\pi}{8}\right) + - \frac{1}{10}$$
=
$$\frac{\pi n}{2} - \frac{1}{10} + \frac{\pi}{8}$$
substitute to the expression
$$\tan{\left(2 x \right)} \leq 1$$
$$\tan{\left(2 \left(\frac{\pi n}{2} - \frac{1}{10} + \frac{\pi}{8}\right) \right)} \leq 1$$
   /  1   pi       \     
tan|- - + -- + pi*n| <= 1
   \  5   4        /     

the solution of our inequality is:
$$x \leq \frac{\pi n}{2} + \frac{\pi}{8}$$
 _____          
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       x1
Solving inequality on a graph
Rapid solution 2 [src]
        /   ___________\            
        |  /       ___ |            
        |\/  2 - \/ 2  |     pi  pi 
[0, atan|--------------|] U (--, --]
        |   ___________|     4   2  
        |  /       ___ |            
        \\/  2 + \/ 2  /            
$$x\ in\ \left[0, \operatorname{atan}{\left(\frac{\sqrt{2 - \sqrt{2}}}{\sqrt{\sqrt{2} + 2}} \right)}\right] \cup \left(\frac{\pi}{4}, \frac{\pi}{2}\right]$$
x in Union(Interval(0, atan(sqrt(2 - sqrt(2))/sqrt(sqrt(2) + 2))), Interval.Lopen(pi/4, pi/2))
Rapid solution [src]
  /   /                 /   ___________\\                      \
  |   |                 |  /       ___ ||                      |
  |   |                 |\/  2 - \/ 2  ||     /     pi  pi    \|
Or|And|0 <= x, x <= atan|--------------||, And|x <= --, -- < x||
  |   |                 |   ___________||     \     2   4     /|
  |   |                 |  /       ___ ||                      |
  \   \                 \\/  2 + \/ 2  //                      /
$$\left(0 \leq x \wedge x \leq \operatorname{atan}{\left(\frac{\sqrt{2 - \sqrt{2}}}{\sqrt{\sqrt{2} + 2}} \right)}\right) \vee \left(x \leq \frac{\pi}{2} \wedge \frac{\pi}{4} < x\right)$$
((x <= pi/2)∧(pi/4 < x))∨((0 <= x)∧(x <= atan(sqrt(2 - sqrt(2))/sqrt(2 + sqrt(2)))))