Express the Limit as a Definite Integral on the Given $\lim _{n \rightarrow \infty} \sum_{i=1}^{n}\left(3 r_{i} \sin r_{i}\right) \Delta r$

Short Answer

Express the limit as a definite integral on the given interval. $\lim _{n \rightarrow \infty} \sum_{i=1}^{n}\left(3 r_{i} \sin r_{i}\right) \Delta r$ $\quad \quad [3,11]$