question_answer

The value of \[\mathbf{tan}\,\mathbf{10}{}^\circ .\mathbf{tan}\text{ }\mathbf{20}{}^\circ .\mathbf{tan}\,\mathbf{30}{}^\circ .\mathbf{tan}\,\mathbf{45}{}^\circ .\]\[\mathbf{tan}\,\mathbf{60}{}^\circ .\mathbf{tan}\,\mathbf{70}{}^\circ .\mathbf{tan}\,\mathbf{80}{}^\circ \]is:

A)  0        

B)                               \[-\]1       

C)    1       

D)                                                       2

E)  None of these