Mister Exam

ctg(x)>-1 inequation

A inequation with variable

The solution

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

the solution of our inequality is:
$$x < - \frac{\pi}{4}$$
 _____          
      \    
-------ο-------
       x1
Rapid solution [src]
   /           3*pi\
And|0 < x, x < ----|
   \            4  /
$$0 < x \wedge x < \frac{3 \pi}{4}$$
(0 < x)∧(x < 3*pi/4)
Rapid solution 2 [src]
    3*pi 
(0, ----)
     4   
$$x\ in\ \left(0, \frac{3 \pi}{4}\right)$$
x in Interval.open(0, 3*pi/4)