You could use the Auto Expire module.


  This module allows site administrators to set expiration times for content types.
  
  End users creating content that has auto expiry set cannot control the expiry time. They could be allowed to renew the content for one or more cycles.
  
  Before a node is expired a warning message is sent to the user that created that node. If the user has the proper rights he can then extend the node.


How do I delete nodes older than X days?
How to find the distance using dot product from point $A$ to the line through $B$ and $C$?

The points are $A = (2, -6, 1)$, $B = (3, 4, -2)$ and $C = (7, -1, 5)$.

I have tried this method: $$d=\frac{||BC \times BA||}{||BC||}$$

Please tell me how to find the distance using dot product.
