Mister Exam

ctg2x<1 inequation

A inequation with variable

The solution

You have entered [src]
cot(2*x) < 1
$$\cot{\left(2 x \right)} < 1$$
cot(2*x) < 1
Detail solution
Given the inequality:
$$\cot{\left(2 x \right)} < 1$$
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:
$$x_{0} < x_{1}$$
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
$$\cot{\left(2 x \right)} < 1$$
$$\cot{\left(2 \left(- \frac{1}{10} + \frac{\pi}{8}\right) \right)} < 1$$
   /1   pi\    
tan|- + --| < 1
   \5   4 /    

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

Then
$$x < \frac{\pi}{8}$$
no execute
the solution of our inequality is:
$$x > \frac{\pi}{8}$$
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       x1
Rapid solution [src]
   /            /   ___________\    \
   |            |  /       ___ |    |
   |    pi      |\/  2 - \/ 2  |    |
And|x < --, atan|--------------| < x|
   |    2       |   ___________|    |
   |            |  /       ___ |    |
   \            \\/  2 + \/ 2  /    /
$$x < \frac{\pi}{2} \wedge \operatorname{atan}{\left(\frac{\sqrt{2 - \sqrt{2}}}{\sqrt{\sqrt{2} + 2}} \right)} < x$$
(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.open(atan(sqrt(2 - sqrt(2))/sqrt(sqrt(2) + 2)), pi/2)