Mister Exam

cot(x/4)<1 inequation

A inequation with variable

The solution

You have entered [src]
   /x\    
cot|-| < 1
   \4/    
$$\cot{\left(\frac{x}{4} \right)} < 1$$
cot(x/4) < 1
Detail solution
Given the inequality:
$$\cot{\left(\frac{x}{4} \right)} < 1$$
To solve this inequality, we must first solve the corresponding equation:
$$\cot{\left(\frac{x}{4} \right)} = 1$$
Solve:
$$x_{1} = \pi$$
$$x_{1} = \pi$$
This roots
$$x_{1} = \pi$$
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
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$- \frac{1}{10} + \pi$$
=
$$- \frac{1}{10} + \pi$$
substitute to the expression
$$\cot{\left(\frac{x}{4} \right)} < 1$$
$$\cot{\left(\frac{- \frac{1}{10} + \pi}{4} \right)} < 1$$
   /1    pi\    
tan|-- + --| < 1
   \40   4 /    

but
   /1    pi\    
tan|-- + --| > 1
   \40   4 /    

Then
$$x < \pi$$
no execute
the solution of our inequality is:
$$x > \pi$$
         _____  
        /
-------ο-------
       x1
Rapid solution [src]
And(pi < x, x < 4*pi)
$$\pi < x \wedge x < 4 \pi$$
(pi < x)∧(x < 4*pi)
Rapid solution 2 [src]
(pi, 4*pi)
$$x\ in\ \left(\pi, 4 \pi\right)$$
x in Interval.open(pi, 4*pi)