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If $${\text{tan }}{9^ \circ } = \frac{p}{q}{\text{,}}$$   then the value of $$\frac{{{\text{se}}{{\text{c}}^2}{\text{8}}{{\text{1}}^ \circ }}}{{1 + {{\cot }^2}{{81}^ \circ }}}$$   is?

A. $$\frac{p}{q}$$

B. 1

C. $$\frac{{{p^2}}}{{{q^2}}}$$

D. $$\frac{{{q^2}}}{{{p^2}}}$$

Answer: Option D

Solution(By Examveda Team)

$$\eqalign{ & {\text{ tan }}{9^ \circ } = \frac{p}{q} \cr & \Rightarrow \frac{{{\text{se}}{{\text{c}}^2}{\text{8}}{{\text{1}}^ \circ }}}{{1 + {{\cot }^2}{{81}^ \circ }}} \cr & \Rightarrow \frac{{{\text{se}}{{\text{c}}^2}{\text{8}}{{\text{1}}^ \circ }}}{{{{\operatorname{cosec} }^2}{{81}^ \circ }}} \cr & \Rightarrow \frac{1}{{{\text{co}}{{\text{s}}^2}{{81}^ \circ }}} \times {\sin ^2}{81^ \circ } \cr & \Rightarrow {\text{ta}}{{\text{n}}^2}{81^ \circ } \cr & \Rightarrow {\text{ta}}{{\text{n}}^2}\left( {{{90}^ \circ } - {9^ \circ }} \right) \cr & \Rightarrow {\text{co}}{{\text{t}}^2}{9^ \circ } \cr & \Rightarrow \frac{{{q^2}}}{{{p^2}}} \cr} $$

This Question Belongs to Arithmetic Ability >> Trigonometry

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