Mister Exam

Other calculators


sin(x-pi/3)>=1/2

sin(x-pi/3)>=1/2 inequation

A inequation with variable

The solution

You have entered [src]
   /    pi\       
sin|x - --| >= 1/2
   \    3 /       
$$\sin{\left(x - \frac{\pi}{3} \right)} \geq \frac{1}{2}$$
sin(x - pi/3) >= 1/2
Detail solution
Given the inequality:
$$\sin{\left(x - \frac{\pi}{3} \right)} \geq \frac{1}{2}$$
To solve this inequality, we must first solve the corresponding equation:
$$\sin{\left(x - \frac{\pi}{3} \right)} = \frac{1}{2}$$
Solve:
Given the equation
$$\sin{\left(x - \frac{\pi}{3} \right)} = \frac{1}{2}$$
- this is the simplest trigonometric equation
Divide both parts of the equation by $-1$
The equation is transformed to
$$\cos{\left(x + \frac{\pi}{6} \right)} = - \frac{1}{2}$$
This equation is transformed to
$$x + \frac{\pi}{6} = 2 \pi n + \operatorname{acos}{\left(- \frac{1}{2} \right)}$$
$$x + \frac{\pi}{6} = 2 \pi n - \pi + \operatorname{acos}{\left(- \frac{1}{2} \right)}$$
Or
$$x + \frac{\pi}{6} = 2 \pi n + \frac{2 \pi}{3}$$
$$x + \frac{\pi}{6} = 2 \pi n - \frac{\pi}{3}$$
, where n - is a integer
Move
$$\frac{\pi}{6}$$
to right part of the equation with the opposite sign, in total:
$$x = 2 \pi n + \frac{\pi}{2}$$
$$x = 2 \pi n - \frac{\pi}{2}$$
$$x_{1} = 2 \pi n + \frac{\pi}{2}$$
$$x_{2} = 2 \pi n - \frac{\pi}{2}$$
$$x_{1} = 2 \pi n + \frac{\pi}{2}$$
$$x_{2} = 2 \pi n - \frac{\pi}{2}$$
This roots
$$x_{1} = 2 \pi n + \frac{\pi}{2}$$
$$x_{2} = 2 \pi n - \frac{\pi}{2}$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} \leq x_{1}$$
For example, let's take the point
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$\left(2 \pi n + \frac{\pi}{2}\right) - \frac{1}{10}$$
=
$$2 \pi n - \frac{1}{10} + \frac{\pi}{2}$$
substitute to the expression
$$\sin{\left(x - \frac{\pi}{3} \right)} \geq \frac{1}{2}$$
$$\sin{\left(\left(2 \pi n - \frac{1}{10} + \frac{\pi}{2}\right) - \frac{\pi}{3} \right)} \geq \frac{1}{2}$$
   /1    pi\       
cos|-- + --| >= 1/2
   \10   3 /       

but
   /1    pi\      
cos|-- + --| < 1/2
   \10   3 /      

Then
$$x \leq 2 \pi n + \frac{\pi}{2}$$
no execute
one of the solutions of our inequality is:
$$x \geq 2 \pi n + \frac{\pi}{2} \wedge x \leq 2 \pi n - \frac{\pi}{2}$$
         _____  
        /     \  
-------•-------•-------
       x_1      x_2
Solving inequality on a graph
Rapid solution [src]
   /        /                                                               /       _____________________________________________________________________________________________________________________________\\       \
   |        |  /         /                 /              -pi*I \   \\      |      /         /              -pi*I \        /              -pi*I \        /              -pi*I \           /              -pi*I \ ||       |
   |        |  |         |                 |   _________  ------|   ||      |     /          |   _________  ------|        |   _________  ------|        |   _________  ------|           |   _________  ------| ||       |
   |        |  |         |           ___   |  /  3 ____     3   |   ||      |    /           |  /  3 ____     3   |       2|  /  3 ____     3   |       2|  /  3 ____     3   |     ___   |  /  3 ____     3   | ||       |
   |        |  |         |   1 + 2*\/ 3 *im\\/  -\/ -1  *e      /   ||      |   /    1   3*re\\/  -\/ -1  *e      /   3*im \\/  -\/ -1  *e      /   3*re \\/  -\/ -1  *e      /   \/ 3 *im\\/  -\/ -1  *e      / ||       |
And|x <= -I*|I*|pi + atan|------------------------------------------|| + log|  /     - - -------------------------- + --------------------------- + --------------------------- + ------------------------------ ||, 0 < x|
   |        |  |         |                    /              -pi*I \||      \\/      4               4                             4                             4                              4                /|       |
   |        |  |         |                    |   _________  ------|||                                                                                                                                            |       |
   |        |  |         |    ___       ___   |  /  3 ____     3   |||                                                                                                                                            |       |
   \        \  \         \- \/ 3  + 2*\/ 3 *re\\/  -\/ -1  *e      ///                                                                                                                                            /       /
$$x \leq - i \left(\log{\left(\sqrt{\frac{\sqrt{3} \operatorname{im}{\left(\sqrt{- \sqrt[3]{-1}} e^{- \frac{i \pi}{3}}\right)}}{4} + \frac{3 \left(\operatorname{re}{\left(\sqrt{- \sqrt[3]{-1}} e^{- \frac{i \pi}{3}}\right)}\right)^{2}}{4} + \frac{1}{4} - \frac{3 \operatorname{re}{\left(\sqrt{- \sqrt[3]{-1}} e^{- \frac{i \pi}{3}}\right)}}{4} + \frac{3 \left(\operatorname{im}{\left(\sqrt{- \sqrt[3]{-1}} e^{- \frac{i \pi}{3}}\right)}\right)^{2}}{4}} \right)} + i \left(\operatorname{atan}{\left(\frac{2 \sqrt{3} \operatorname{im}{\left(\sqrt{- \sqrt[3]{-1}} e^{- \frac{i \pi}{3}}\right)} + 1}{- \sqrt{3} + 2 \sqrt{3} \operatorname{re}{\left(\sqrt{- \sqrt[3]{-1}} e^{- \frac{i \pi}{3}}\right)}} \right)} + \pi\right)\right) \wedge 0 < x$$
(0 < x)∧(x <= -i*(i*(pi + atan((1 + 2*sqrt(3)*im(sqrt(-(-1)^(1/3))*exp(-pi*i/3)))/(-sqrt(3) + 2*sqrt(3)*re(sqrt(-(-1)^(1/3))*exp(-pi*i/3))))) + log(sqrt(1/4 - 3*re(sqrt(-(-1)^(1/3))*exp(-pi*i/3))/4 + 3*im(sqrt(-(-1)^(1/3))*exp(-pi*i/3))^2/4 + 3*re(sqrt(-(-1)^(1/3))*exp(-pi*i/3))^2/4 + sqrt(3)*im(sqrt(-(-1)^(1/3))*exp(-pi*i/3))/4))))
The graph
sin(x-pi/3)>=1/2 inequation