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cost>1/2 inequation

A inequation with variable

The solution

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cos(t) > 1/2
$$\cos{\left(t \right)} > \frac{1}{2}$$
cos(t) > 1/2
Detail solution
Given the inequality:
$$\cos{\left(t \right)} > \frac{1}{2}$$
To solve this inequality, we must first solve the corresponding equation:
$$\cos{\left(t \right)} = \frac{1}{2}$$
Solve:
Given the equation
$$\cos{\left(t \right)} = \frac{1}{2}$$
- this is the simplest trigonometric equation
This equation is transformed to
$$t = \pi n + \operatorname{acos}{\left(\frac{1}{2} \right)}$$
$$t = \pi n - \pi + \operatorname{acos}{\left(\frac{1}{2} \right)}$$
Or
$$t = \pi n + \frac{\pi}{3}$$
$$t = \pi n - \frac{2 \pi}{3}$$
, where n - is a integer
$$t_{1} = \pi n + \frac{\pi}{3}$$
$$t_{2} = \pi n - \frac{2 \pi}{3}$$
$$t_{1} = \pi n + \frac{\pi}{3}$$
$$t_{2} = \pi n - \frac{2 \pi}{3}$$
This roots
$$t_{1} = \pi n + \frac{\pi}{3}$$
$$t_{2} = \pi n - \frac{2 \pi}{3}$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$t_{0} < t_{1}$$
For example, let's take the point
$$t_{0} = t_{1} - \frac{1}{10}$$
=
$$\left(\pi n + \frac{\pi}{3}\right) + - \frac{1}{10}$$
=
$$\pi n - \frac{1}{10} + \frac{\pi}{3}$$
substitute to the expression
$$\cos{\left(t \right)} > \frac{1}{2}$$
$$\cos{\left(\pi n - \frac{1}{10} + \frac{\pi}{3} \right)} > \frac{1}{2}$$
   /  1    pi       \      
cos|- -- + -- + pi*n| > 1/2
   \  10   3        /      

Then
$$t < \pi n + \frac{\pi}{3}$$
no execute
one of the solutions of our inequality is:
$$t > \pi n + \frac{\pi}{3} \wedge t < \pi n - \frac{2 \pi}{3}$$
         _____  
        /     \  
-------ο-------ο-------
       t1      t2
Solving inequality on a graph
Rapid solution 2 [src]
    pi     5*pi       
[0, --) U (----, 2*pi]
    3       3         
$$t\ in\ \left[0, \frac{\pi}{3}\right) \cup \left(\frac{5 \pi}{3}, 2 \pi\right]$$
t in Union(Interval.Ropen(0, pi/3), Interval.Lopen(5*pi/3, 2*pi))
Rapid solution [src]
  /   /            pi\     /           5*pi    \\
Or|And|0 <= t, t < --|, And|t <= 2*pi, ---- < t||
  \   \            3 /     \            3      //
$$\left(0 \leq t \wedge t < \frac{\pi}{3}\right) \vee \left(t \leq 2 \pi \wedge \frac{5 \pi}{3} < t\right)$$
((0 <= t)∧(t < pi/3))∨((t <= 2*pi)∧(5*pi/3 < t))