What are sigma and sigma_1 in problem 6.2 of Goldstein?

[ehrenfest]

Homework Statement

http://books.google.com/books?id=Xm...42EpgKaxsi5Dw&sig=6cUrZKqmPMoe0QBRTSYNnipNRw4
For problem 6.2, in the expression x = a sigma/ sigma_1, sigma is the spatial parameter but what is sigma_1 and is a the x-coordinate of one endpoint of the string?

Also, can someone give the first step I should take in order to solve this problem?

Homework Equations

The Attempt at a Solution

 

[ehrenfest]

does my question make sense to people?

 

[nrqed]

Homework Statement

http://books.google.com/books?id=Xm...42EpgKaxsi5Dw&sig=6cUrZKqmPMoe0QBRTSYNnipNRw4
For problem 6.2, in the expression x = a sigma/ sigma_1, sigma is the spatial parameter but what is sigma_1 and is a the x-coordinate of one endpoint of the string?

Also, can someone give the first step I should take in order to solve this problem?

Homework Equations

The Attempt at a Solution

zwiebach uses the somewhat confusing notation that for an open string, sigma ranges from 0 to $\sigma_1$ so $\sigma_1$ is indeed the coordinate corresponding to the extremity of the string. Therefore x ranges from 0 to a (so a is the length of the string).