Mister Exam

ctg(x)≥√3 inequation

A inequation with variable

The solution

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cot(x) >= \/ 3 
cot(x)3\cot{\left(x \right)} \geq \sqrt{3}
cot(x) >= sqrt(3)
Detail solution
Given the inequality:
cot(x)3\cot{\left(x \right)} \geq \sqrt{3}
To solve this inequality, we must first solve the corresponding equation:
cot(x)=3\cot{\left(x \right)} = \sqrt{3}
Solve:
Given the equation
cot(x)=3\cot{\left(x \right)} = \sqrt{3}
transform
cot(x)31=0\cot{\left(x \right)} - \sqrt{3} - 1 = 0
cot(x)31=0\cot{\left(x \right)} - \sqrt{3} - 1 = 0
Do replacement
w=cot(x)w = \cot{\left(x \right)}
Expand brackets in the left part
-1 + w - sqrt3 = 0

Move free summands (without w)
from left part to right part, we given:
w3=1w - \sqrt{3} = 1
Divide both parts of the equation by (w - sqrt(3))/w
w = 1 / ((w - sqrt(3))/w)

We get the answer: w = 1 + sqrt(3)
do backward replacement
cot(x)=w\cot{\left(x \right)} = w
substitute w:
x1=π6x_{1} = \frac{\pi}{6}
x1=π6x_{1} = \frac{\pi}{6}
This roots
x1=π6x_{1} = \frac{\pi}{6}
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
x0x1x_{0} \leq x_{1}
For example, let's take the point
x0=x1110x_{0} = x_{1} - \frac{1}{10}
=
110+π6- \frac{1}{10} + \frac{\pi}{6}
=
110+π6- \frac{1}{10} + \frac{\pi}{6}
substitute to the expression
cot(x)3\cot{\left(x \right)} \geq \sqrt{3}
cot(110+π6)3\cot{\left(- \frac{1}{10} + \frac{\pi}{6} \right)} \geq \sqrt{3}
   /1    pi\      ___
tan|-- + --| >= \/ 3 
   \10   3 /    

the solution of our inequality is:
xπ6x \leq \frac{\pi}{6}
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       x1
Rapid solution 2 [src]
    pi 
(0, --]
    6  
x in (0,π6]x\ in\ \left(0, \frac{\pi}{6}\right]
x in Interval.Lopen(0, pi/6)
Rapid solution [src]
   /     pi       \
And|x <= --, 0 < x|
   \     6        /
xπ60<xx \leq \frac{\pi}{6} \wedge 0 < x
(0 < x)∧(x <= pi/6)