Select the correct answer.

What is the exact value of [tex]$\tan 75^{\circ}$[/tex]?

A. [tex]\frac{1-\frac{\sqrt{3}}{3}}{1+\frac{\sqrt{3}}{3}}[/tex]
B. [tex]\frac{1+\frac{\sqrt{3}}{3}}{1-\frac{\sqrt{3}}{3}}[/tex]
C. [tex]\frac{1+\sqrt{3}}{1-\sqrt{3}}[/tex]
D. [tex]\frac{1-\sqrt{3}}{1+\sqrt{3}}[/tex]



Answer :

To find the exact value of [tex]\(\tan 75^\circ\)[/tex], we can use the tangent addition formula. Specifically, we know that:

[tex]\[ 75^\circ = 45^\circ + 30^\circ \][/tex]

The tangent addition formula is:

[tex]\[ \tan(a + b) = \frac{\tan a + \tan b}{1 - \tan a \tan b} \][/tex]

Applying this to [tex]\(a = 45^\circ\)[/tex] and [tex]\(b = 30^\circ\)[/tex]:

1. We know that:
[tex]\[ \tan 45^\circ = 1 \][/tex]
[tex]\[ \tan 30^\circ = \frac{1}{\sqrt{3}} = \frac{\sqrt{3}}{3} \][/tex]

2. Now, substitute these values into the tangent addition formula:
[tex]\[ \tan 75^\circ = \frac{\tan 45^\circ + \tan 30^\circ}{1 - \tan 45^\circ \tan 30^\circ} \][/tex]
[tex]\[ \tan 75^\circ = \frac{1 + \frac{\sqrt{3}}{3}}{1 - 1 \cdot \frac{\sqrt{3}}{3}} \][/tex]

3. Simplify the expression:
[tex]\[ \tan 75^\circ = \frac{1 + \frac{\sqrt{3}}{3}}{1 - \frac{\sqrt{3}}{3}} \][/tex]

Thus, the correct answer is:

[tex]\[ \boxed{\frac{1+\frac{\sqrt{3}}{3}}{1-\frac{\sqrt{3}}{3}}} \][/tex]
The corresponding option in the given choices is:

B. [tex]\(\frac{1+\frac{\sqrt{3}}{3}}{1-\frac{\sqrt{3}}{3}}\)[/tex]