Question

tg n/7 * ctg n/7 - sin n/6

Answer 1

$tg\frac{\pi} {7} *ctg\frac{\pi} {7}-sin\frac{\pi} {6}=\frac{sin\frac{\pi} {7} }{cos\frac{\pi} {7} } *\frac{cos\frac{\pi} {7} }{sin\frac{\pi} {7} } -sin\frac{\pi} {6}=1-\frac{1}{2} =\frac{1}{2}$