Mister Exam

tg(3x)<3 inequation

A inequation with variable

The solution

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

the solution of our inequality is:
$$x < \frac{\pi n}{3} + \frac{\operatorname{atan}{\left(3 \right)}}{3}$$
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Solving inequality on a graph
Rapid solution [src]
  /   /               /      /   /  atan(3/4)   pi\\                                                             \\                      \
  |   |               |      |sin|- --------- + --||      /    _________________________________________________\||                      |
  |   |               |      |   \      6       6 /|      |   /    2/  atan(3/4)   pi\      2/  atan(3/4)   pi\ |||     /     pi  pi    \|
Or|And|0 <= x, x < -I*|I*atan|---------------------| + log|  /  cos |- --------- + --| + sin |- --------- + --| |||, And|x <= --, -- < x||
  |   |               |      |   /  atan(3/4)   pi\|      \\/       \      6       6 /       \      6       6 / /||     \     3   6     /|
  |   |               |      |cos|- --------- + --||                                                             ||                      |
  \   \               \      \   \      6       6 //                                                             //                      /
$$\left(0 \leq x \wedge x < - i \left(\log{\left(\sqrt{\sin^{2}{\left(- \frac{\operatorname{atan}{\left(\frac{3}{4} \right)}}{6} + \frac{\pi}{6} \right)} + \cos^{2}{\left(- \frac{\operatorname{atan}{\left(\frac{3}{4} \right)}}{6} + \frac{\pi}{6} \right)}} \right)} + i \operatorname{atan}{\left(\frac{\sin{\left(- \frac{\operatorname{atan}{\left(\frac{3}{4} \right)}}{6} + \frac{\pi}{6} \right)}}{\cos{\left(- \frac{\operatorname{atan}{\left(\frac{3}{4} \right)}}{6} + \frac{\pi}{6} \right)}} \right)}\right)\right) \vee \left(x \leq \frac{\pi}{3} \wedge \frac{\pi}{6} < x\right)$$
((x <= pi/3)∧(pi/6 < x))∨((0 <= x)∧(x < -i*(i*atan(sin(-atan(3/4)/6 + pi/6)/cos(-atan(3/4)/6 + pi/6)) + log(sqrt(cos(-atan(3/4)/6 + pi/6)^2 + sin(-atan(3/4)/6 + pi/6)^2)))))