kill(all)$

van=facebook.com/LearningCalculus$

theta(k,n):=%pi/n;

s(n):=sum(sin(theta(i,n)),i,1,n);

p(n):=prod(tan(theta(i,n)),i,1,n);

f(n):=s(n)/(cos(%pi/n)*p(n)^(1/n))$ f(n);

f(2016);

trigsimp(%);