Question

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

Answer 1

$tgfrac{pi} {7} *ctgfrac{pi} {7}-sinfrac{pi} {6}=frac{sinfrac{pi} {7} }{cosfrac{pi} {7} } *frac{cosfrac{pi} {7} }{sinfrac{pi} {7} } -sinfrac{pi} {6}=1-frac{1}{2} =frac{1}{2}$