Mister Exam

tg3x>-2 inequation

A inequation with variable

The solution

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tan(3*x) > -2
$$\tan{\left(3 x \right)} > -2$$
tan(3*x) > -2
Detail solution
Given the inequality:
$$\tan{\left(3 x \right)} > -2$$
To solve this inequality, we must first solve the corresponding equation:
$$\tan{\left(3 x \right)} = -2$$
Solve:
Given the equation
$$\tan{\left(3 x \right)} = -2$$
- this is the simplest trigonometric equation
This equation is transformed to
$$3 x = \pi n + \operatorname{atan}{\left(-2 \right)}$$
Or
$$3 x = \pi n - \operatorname{atan}{\left(2 \right)}$$
, where n - is a integer
Divide both parts of the equation by
$$3$$
$$x_{1} = \frac{\pi n}{3} - \frac{\operatorname{atan}{\left(2 \right)}}{3}$$
$$x_{1} = \frac{\pi n}{3} - \frac{\operatorname{atan}{\left(2 \right)}}{3}$$
This roots
$$x_{1} = \frac{\pi n}{3} - \frac{\operatorname{atan}{\left(2 \right)}}{3}$$
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
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$\left(\frac{\pi n}{3} - \frac{\operatorname{atan}{\left(2 \right)}}{3}\right) + - \frac{1}{10}$$
=
$$\frac{\pi n}{3} - \frac{\operatorname{atan}{\left(2 \right)}}{3} - \frac{1}{10}$$
substitute to the expression
$$\tan{\left(3 x \right)} > -2$$
$$\tan{\left(3 \left(\frac{\pi n}{3} - \frac{\operatorname{atan}{\left(2 \right)}}{3} - \frac{1}{10}\right) \right)} > -2$$
-tan(3/10 - pi*n + atan(2)) > -2

Then
$$x < \frac{\pi n}{3} - \frac{\operatorname{atan}{\left(2 \right)}}{3}$$
no execute
the solution of our inequality is:
$$x > \frac{\pi n}{3} - \frac{\operatorname{atan}{\left(2 \right)}}{3}$$
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Solving inequality on a graph
Rapid solution [src]
  /                        /            /      /     /  atan(4/3)   pi\     ___    /  atan(4/3)   pi\\                                                             \    \\
  |                        |            |      |- sin|- --------- + --| + \/ 3 *cos|- --------- + --||      /    _________________________________________________\|    ||
  |   /            pi\     |     pi     |      |     \      6       6 /            \      6       6 /|      |   /    2/  atan(4/3)   pi\      2/  atan(4/3)   pi\ ||    ||
Or|And|0 <= x, x < --|, And|x <= --, -I*|I*atan|-----------------------------------------------------| + log|  /  cos |- --------- + --| + sin |- --------- + --| || < x||
  |   \            6 /     |     3      |      |   ___    /  atan(4/3)   pi\      /  atan(4/3)   pi\ |      \\/       \      6       6 /       \      6       6 / /|    ||
  |                        |            |      | \/ 3 *sin|- --------- + --| + cos|- --------- + --| |                                                             |    ||
  \                        \            \      \          \      6       6 /      \      6       6 / /                                                             /    //
$$\left(0 \leq x \wedge x < \frac{\pi}{6}\right) \vee \left(x \leq \frac{\pi}{3} \wedge - i \left(\log{\left(\sqrt{\sin^{2}{\left(- \frac{\operatorname{atan}{\left(\frac{4}{3} \right)}}{6} + \frac{\pi}{6} \right)} + \cos^{2}{\left(- \frac{\operatorname{atan}{\left(\frac{4}{3} \right)}}{6} + \frac{\pi}{6} \right)}} \right)} + i \operatorname{atan}{\left(\frac{- \sin{\left(- \frac{\operatorname{atan}{\left(\frac{4}{3} \right)}}{6} + \frac{\pi}{6} \right)} + \sqrt{3} \cos{\left(- \frac{\operatorname{atan}{\left(\frac{4}{3} \right)}}{6} + \frac{\pi}{6} \right)}}{\sqrt{3} \sin{\left(- \frac{\operatorname{atan}{\left(\frac{4}{3} \right)}}{6} + \frac{\pi}{6} \right)} + \cos{\left(- \frac{\operatorname{atan}{\left(\frac{4}{3} \right)}}{6} + \frac{\pi}{6} \right)}} \right)}\right) < x\right)$$
((0 <= x)∧(x < pi/6))∨((x <= pi/3)∧(-i*(i*atan((-sin(-atan(4/3)/6 + pi/6) + sqrt(3)*cos(-atan(4/3)/6 + pi/6))/(sqrt(3)*sin(-atan(4/3)/6 + pi/6) + cos(-atan(4/3)/6 + pi/6))) + log(sqrt(cos(-atan(4/3)/6 + pi/6)^2 + sin(-atan(4/3)/6 + pi/6)^2))) < x))