Prove the following equality: $4 sin\frac{2\pi }{7}-tg \frac{\pi }{7}=\sqrt{7}$
Problem
Source: I International Festival of Young Mathematicians Sozopol 2010, Theme for 10-12 grade
Tags: algebra, Trigonometric Equations
Source: I International Festival of Young Mathematicians Sozopol 2010, Theme for 10-12 grade
Tags: algebra, Trigonometric Equations
Prove the following equality: $4 sin\frac{2\pi }{7}-tg \frac{\pi }{7}=\sqrt{7}$