Good Bye 2015 - 1
Geometry
Level
4
\[ \large \dfrac{3 - \tan^2\left( \dfrac\pi7 \right)}{1 - \tan^2\left( \dfrac\pi7 \right)} \div \cos\left( \dfrac\pi7 \right) = \, ? \]
by
Surya Prakash