Mister Exam

ctg(2x)<=1 inequation

A inequation with variable

The solution

You have entered [src]
cot(2*x) <= 1
$$\cot{\left(2 x \right)} \leq 1$$
cot(2*x) <= 1
Detail solution
Given the inequality:
$$\cot{\left(2 x \right)} \leq 1$$
To solve this inequality, we must first solve the corresponding equation:
$$\cot{\left(2 x \right)} = 1$$
Solve:
Given the equation
$$\cot{\left(2 x \right)} = 1$$
transform
$$\cot{\left(2 x \right)} - 1 = 0$$
$$\cot{\left(2 x \right)} - 1 = 0$$
Do replacement
$$w = \cot{\left(2 x \right)}$$
Move free summands (without w)
from left part to right part, we given:
$$w = 1$$
We get the answer: w = 1
do backward replacement
$$\cot{\left(2 x \right)} = w$$
substitute w:
$$x_{1} = \frac{\pi}{8}$$
$$x_{1} = \frac{\pi}{8}$$
This roots
$$x_{1} = \frac{\pi}{8}$$
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
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$- \frac{1}{10} + \frac{\pi}{8}$$
=
$$- \frac{1}{10} + \frac{\pi}{8}$$
substitute to the expression
$$\cot{\left(2 x \right)} \leq 1$$
$$\cot{\left(2 \left(- \frac{1}{10} + \frac{\pi}{8}\right) \right)} \leq 1$$
   /1   pi\     
tan|- + --| <= 1
   \5   4 /     

but
   /1   pi\     
tan|- + --| >= 1
   \5   4 /     

Then
$$x \leq \frac{\pi}{8}$$
no execute
the solution of our inequality is:
$$x \geq \frac{\pi}{8}$$
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Rapid solution [src]
   /    /   ___________\             \
   |    |  /       ___ |             |
   |    |\/  2 - \/ 2  |           pi|
And|atan|--------------| <= x, x < --|
   |    |   ___________|           2 |
   |    |  /       ___ |             |
   \    \\/  2 + \/ 2  /             /
$$\operatorname{atan}{\left(\frac{\sqrt{2 - \sqrt{2}}}{\sqrt{\sqrt{2} + 2}} \right)} \leq x \wedge x < \frac{\pi}{2}$$
(x < pi/2)∧(atan(sqrt(2 - sqrt(2))/sqrt(2 + sqrt(2))) <= x)
Rapid solution 2 [src]
     /   ___________\     
     |  /       ___ |     
     |\/  2 - \/ 2  |  pi 
[atan|--------------|, --)
     |   ___________|  2  
     |  /       ___ |     
     \\/  2 + \/ 2  /     
$$x\ in\ \left[\operatorname{atan}{\left(\frac{\sqrt{2 - \sqrt{2}}}{\sqrt{\sqrt{2} + 2}} \right)}, \frac{\pi}{2}\right)$$
x in Interval.Ropen(atan(sqrt(2 - sqrt(2))/sqrt(sqrt(2) + 2)), pi/2)