Yahoo Inc (YHOO.O) and Microsoft Corp (MSFT.O) agreed to extend by 30 days the deadline to re-negotiate a ten year search deal, as the two Internet companies attempt to revamp a thorny partnership crafted by former chief executives. The search partnership, which took effect in 2010, allowed the companies to negotiate changes or to terminate the arrangement entirely after five years. According to a filing with the U.S. Securities and Exchange Commission on Friday, Yahoo and Microsoft mutually agreed to extend that deadline to a 60-day period following Feb. 23.