"The ambiance of the crowd was crazy," said Cost, a native of France who made two free throws with 5.5 seconds left to give the Wildcats (20-6, 8-0 in league) a 56-53 lead. "It's a good place to play and I knew that I could make both of those shots with the crowd yelling.
"We are happy to win league and now we can get focused on the playoffs."
The Wildcats, who won their 15th game in a row and swept the two-game season series against Ribet (15-12, 6-2), took a 54-47 lead with 1:37 remaining on a basket by Gerrick Uneau. However, the Frogs, who captured the CIF Southern Section Division 6-AA championship last season and are coached by Glendale resident William Middlebrooks, made a late comeback by closing to within 54-53 with 41 seconds left on a three-pointer by King Brown.
After Cost made both of his free throws, the Frogs, who had their four-game winning streak stopped, raced toward midcourt but couldn't launch a game-tying shot.
Renaissance Coach Sid Cooke, whose team is ranked fifth with Brethren Christian in the latest Division 5-A poll, said he expected a late surge by the Frogs, ranked No. 9.
"Ribet made some tough shots down the stretch," said Cooke, whose squad posted a 61-51 home win against Ribet on Jan. 28. "It's good to win league and do it on the road.
"We've had different guys being able to step up all year. I like the balance and there's nobody out there trying to be a superstar. Anthony has been solid for us the whole season and we needed him to step up tonight."
Cost, a senior guard, made a three-pointer to give the Wildcats a 50-42 lead with 4:10 left in the fourth quarter.
Cost had six assists in the second half after helping the Wildcats to a 31-28 halftime lead.
"I like to be able to do whatever I can to help make my teammates better," Cost said. "If I can make the assists, then I'm doing good."
In addition to Cost, the Wildcats received plenty of strong performances. Renaissance got 17 points from center Jessy Cantinol, nine points and three steals from guard Nick Troplant and eight points from guard Troy Fontanilla.