Help with cd commands

[TAN Boon Kien]

I have enabled a user to use sudo to cd to a protected directory which he
does not have any access to.  The line in the sudoers file is as follows :
userA LOCALUNIX=/usr/bin/cd /Protected_directory

When this user cd to this directory from his current location using sudo
/usr/bin/cd /Protected_directory,  the sudo did not returned error message
or warning.  However when doing a pwd, the path still shows his current
location instead of the directory which he wants to cd to.  

Appreciate some advice.  Thank you.