Here are some links to help.
https://www.google.com/images?q=bear...d=0CAkQsAQ#i=7
https://www.google.com/images?q=bear...d=0CAkQsAQ#i=5
Typically you want to shoot a touch higher than your instinct says, the reason is bears have fur that hangs down from their belly that makes the vitals appear lower than they are.