Evaluate
From Example 3 (p. 134 in Apostol) we know that the sine and cosine function are continuous. Since and is not zero at , we have that is continuous. Thus, we can take the limit by evaluating at ,
Evaluate
From Example 3 (p. 134 in Apostol) we know that the sine and cosine function are continuous. Since and is not zero at , we have that is continuous. Thus, we can take the limit by evaluating at ,