$\underset{n}{lim}\frac{4}{n}{\displaystyle \underset{i=1}{\overset{n}{}}}sin(\frac{4i}{n}-)=$

${\displaystyle \underset{-1}{\overset{3}{}}}sin(x)dx$

${\displaystyle \underset{-1}{\overset{3}{}}}sin(+x)dx$

${\displaystyle \underset{0}{\overset{4}{}}}sin(x)dx$

${\displaystyle \underset{0}{\overset{4}{}}}sin(x+)dx$