What is the exact value of [tex]\csc \frac{2 \pi}{3}[/tex]?

A. [tex]-2[/tex]
B. [tex]-\frac{\sqrt{3}}{3}[/tex]
C. [tex]\frac{2 \sqrt{3}}{3}[/tex]
D. [tex]\frac{3 \sqrt{2}}{2}[/tex]



Answer :

Let's find the exact value of [tex]\(\csc\left(\frac{2\pi}{3}\right)\)[/tex].

First, recall the definition of the cosecant function:
[tex]\[ \csc(\theta) = \frac{1}{\sin(\theta)} \][/tex]

Next, we need to determine [tex]\(\sin\left(\frac{2\pi}{3}\right)\)[/tex].

The angle [tex]\(\frac{2\pi}{3}\)[/tex] radians is equivalent to 120 degrees. We can use the unit circle or trigonometric identities to find the sine of this angle:
[tex]\[ \sin\left(120^\circ\right) = \sin\left(180^\circ - 60^\circ\right) = \sin\left(60^\circ\right) \][/tex]

From the unit circle, we know that:
[tex]\[ \sin(60^\circ) = \frac{\sqrt{3}}{2} \][/tex]

So:
[tex]\[ \sin\left(\frac{2\pi}{3}\right) = \frac{\sqrt{3}}{2} \][/tex]

Now, we can find [tex]\(\csc\left(\frac{2\pi}{3}\right)\)[/tex]:
[tex]\[ \csc\left(\frac{2\pi}{3}\right) = \frac{1}{\sin\left(\frac{2\pi}{3}\right)} = \frac{1}{\frac{\sqrt{3}}{2}} = \frac{2}{\sqrt{3}} \][/tex]

To rationalize the denominator, multiply the numerator and the denominator by [tex]\(\sqrt{3}\)[/tex]:
[tex]\[ \frac{2}{\sqrt{3}} \cdot \frac{\sqrt{3}}{\sqrt{3}} = \frac{2\sqrt{3}}{3} \][/tex]

Therefore, the exact value of [tex]\(\csc\left(\frac{2\pi}{3}\right)\)[/tex] is:
[tex]\[ \frac{2\sqrt{3}}{3} \][/tex]

The correct answer is:
[tex]\[ \frac{2 \sqrt{3}}{3} \][/tex]