Question

The value of $$\tan A + \tan \left( {{{60}^ \circ } + A} \right) - \tan \left( {{{60}^ \circ } - A} \right){\text{ is}}$$

A. $$\tan 3A$$
B. $$2\tan 3A$$
C. $$3\tan 3A$$  
D. None of these
Answer :   $$3\tan 3A$$
Solution :
The given expression
$$\eqalign{ & = \tan A + \left[ {\frac{{\sqrt 3 + \tan A}}{{1 - \sqrt 3 \tan A}}} \right] - \left[ {\frac{{\sqrt 3 - \tan A}}{{1 + \sqrt 3 \tan A}}} \right] \cr & = \tan A + \left[ {\frac{{8\tan A}}{{1 - 3\,{{\tan }^2}A}}} \right] = \frac{{9\tan A - 3\,{{\tan }^3}\,3}}{{1 - 3\,{{\tan }^2}A}} \cr & = 3 \cdot \frac{{\left( {3\tan A - {{\tan }^3}A} \right)}}{{1 - 3\,{{\tan }^2}A}} = 3\tan 3A \cr} $$

Releted MCQ Question on
Trigonometry >> Trigonometric Ratio and Identities

Releted Question 1

If $$\tan \theta = - \frac{4}{3},$$   then $$\sin \theta $$  is

A. $$ - \frac{4}{5}{\text{ but not }}\frac{4}{5}$$
B. $$ - \frac{4}{5}{\text{ or }}\frac{4}{5}$$
C. $$ \frac{4}{5}{\text{ but not }} - \frac{4}{5}$$
D. None of these
Releted Question 2

If $$\alpha + \beta + \gamma = 2\pi ,$$    then

A. $$\tan \frac{\alpha }{2} + \tan \frac{ \beta }{2} + \tan \frac{\gamma }{2} = \tan \frac{\alpha }{2}\tan \frac{\beta }{2}\tan \frac{\gamma }{2}$$
B. $$\tan \frac{\alpha }{2}\tan \frac{\beta }{2} + \tan \frac{\beta }{2}\tan \frac{\gamma }{2} + \tan \frac{\gamma }{2}\tan \frac{\alpha }{2} = 1$$
C. $$\tan \frac{\alpha }{2} + \tan \frac{ \beta }{2} + \tan \frac{\gamma }{2} = - \tan \frac{\alpha }{2}\tan \frac{\beta }{2}\tan \frac{\gamma }{2}$$
D. None of these
Releted Question 3

Given $$A = {\sin ^2}\theta + {\cos ^4}\theta $$    then for all real values of $$\theta $$

A. $$1 \leqslant A \leqslant 2$$
B. $$\frac{3}{4} \leqslant A \leqslant 1$$
C. $$\frac{13}{16} \leqslant A \leqslant 1$$
D. $$\frac{3}{4} \leqslant A \leqslant \frac{{13}}{{16}}$$
Releted Question 4

The value of the expression $$\sqrt 3 \,{\text{cosec}}\,{\text{2}}{{\text{0}}^ \circ } - \sec {20^ \circ }$$     is equal to

A. 2
B. $$\frac{{2\sin {{20}^ \circ }}}{{\sin {{40}^ \circ }}}$$
C. 4
D. $$\frac{{4\sin {{20}^ \circ }}}{{\sin {{40}^ \circ }}}$$

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