Answer
455.1k+ views
Hint- Try to make the expression of the form $\dfrac{{2\tan \theta }}{{1 + {{\tan }^2}\theta }}$ which is equal to$\sin 2\theta $.
Given: $\tan {15^0} + \tan {75^0}$
Rewriting above as:
$ = {\text{tan1}}{{\text{5}}^0} + \dfrac{1}{{\cot {{75}^0}}}{\text{ }}\left\{ {\because \tan \theta = \dfrac{1}{{\cot \theta }}} \right\}$
Now, using $\tan \theta = \cot \left( {{{90}^0} - \theta } \right)$ to convert $\cot $ into $\tan $, we get
$
\Rightarrow \tan {15^0} + \dfrac{1}{{\cot \left( {{{90}^0} - {{15}^0}} \right)}} \\
\Rightarrow \tan {15^0} + \dfrac{1}{{\tan {{15}^0}}}{\text{ }}\left\{ {\because \tan \theta = \cot \left( {{{90}^0} - \theta } \right)} \right\} \\
$
By cross-Multiplying, we get
$ \Rightarrow \dfrac{{{{\tan }^2}{{15}^0} + 1}}{{\tan {{15}^0}}}$
Multiply and divide by $2$, we get
$
\Rightarrow \dfrac{{2\left[ {{{\tan }^2}{{15}^0} + 1} \right]}}{{2\tan {{15}^0}}} \\
\Rightarrow \dfrac{2}{{\sin 2 \times {{15}^0}}}{\text{ }}\left\{ {\because \dfrac{{2\tan \theta }}{{1 + {{\tan }^2}\theta }} = \sin 2\theta } \right\} \\
\Rightarrow \dfrac{2}{{\sin {{30}^0}}} \\
$
Now, putting the value of $\sin {30^0} = \dfrac{1}{2}$, we get
$
\Rightarrow \dfrac{2}{{\left( {\dfrac{1}{2}} \right)}} \\
\Rightarrow 4 \\
$
$\therefore $ Correct option is $\left( E \right)$
Note- Whenever there are integer angles inside trigonometric functions whose value is not known to us, always try to convert it by using the $\left( {{{90}^0} - \theta } \right)$ form so as to make some trigonometric relations which makes problems much easier to solve.
Given: $\tan {15^0} + \tan {75^0}$
Rewriting above as:
$ = {\text{tan1}}{{\text{5}}^0} + \dfrac{1}{{\cot {{75}^0}}}{\text{ }}\left\{ {\because \tan \theta = \dfrac{1}{{\cot \theta }}} \right\}$
Now, using $\tan \theta = \cot \left( {{{90}^0} - \theta } \right)$ to convert $\cot $ into $\tan $, we get
$
\Rightarrow \tan {15^0} + \dfrac{1}{{\cot \left( {{{90}^0} - {{15}^0}} \right)}} \\
\Rightarrow \tan {15^0} + \dfrac{1}{{\tan {{15}^0}}}{\text{ }}\left\{ {\because \tan \theta = \cot \left( {{{90}^0} - \theta } \right)} \right\} \\
$
By cross-Multiplying, we get
$ \Rightarrow \dfrac{{{{\tan }^2}{{15}^0} + 1}}{{\tan {{15}^0}}}$
Multiply and divide by $2$, we get
$
\Rightarrow \dfrac{{2\left[ {{{\tan }^2}{{15}^0} + 1} \right]}}{{2\tan {{15}^0}}} \\
\Rightarrow \dfrac{2}{{\sin 2 \times {{15}^0}}}{\text{ }}\left\{ {\because \dfrac{{2\tan \theta }}{{1 + {{\tan }^2}\theta }} = \sin 2\theta } \right\} \\
\Rightarrow \dfrac{2}{{\sin {{30}^0}}} \\
$
Now, putting the value of $\sin {30^0} = \dfrac{1}{2}$, we get
$
\Rightarrow \dfrac{2}{{\left( {\dfrac{1}{2}} \right)}} \\
\Rightarrow 4 \\
$
$\therefore $ Correct option is $\left( E \right)$
Note- Whenever there are integer angles inside trigonometric functions whose value is not known to us, always try to convert it by using the $\left( {{{90}^0} - \theta } \right)$ form so as to make some trigonometric relations which makes problems much easier to solve.
Recently Updated Pages
How many sigma and pi bonds are present in HCequiv class 11 chemistry CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Why Are Noble Gases NonReactive class 11 chemistry CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let X and Y be the sets of all positive divisors of class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let x and y be 2 real numbers which satisfy the equations class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let x 4log 2sqrt 9k 1 + 7 and y dfrac132log 2sqrt5 class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let x22ax+b20 and x22bx+a20 be two equations Then the class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Trending doubts
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
At which age domestication of animals started A Neolithic class 11 social science CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Which are the Top 10 Largest Countries of the World?
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Give 10 examples for herbs , shrubs , climbers , creepers
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Difference Between Plant Cell and Animal Cell
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Write a letter to the principal requesting him to grant class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Change the following sentences into negative and interrogative class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Fill in the blanks A 1 lakh ten thousand B 1 million class 9 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)