The Las Vegas City Council has approved moving forward with a study to build a sports arena, an entertainment district and a hotel-casino downtown. Yesterday, the city entered into an agreement with the Baltimore-based Cordish Company. The centerpiece would be a 20-thousand-seat arena, with the hope of luring a pro basketball or hockey team to the city. The two-year agreement calls for Las Vegas to put in up to 150-thousand dollars for studies to evaluate the project. Any work beyond that amount will be paid for by Cordish.