题目

At midnight on December 31, cities around the world welcome the new year with fireworks(烟花) shows. Here are some of this new year’s most wonderful displays.Sydney, AustraliaSydney is well known for its great fireworks. It is also the only city in the world to hold two shows. The first takes place at 9:00 pm to enable families with young kids to celebrate the new year and is broadcast live nationally. The second show at midnight, is enjoyed live internationally.Dubai, UAEDubai is famous for its larger-than-life shows. The record-holder for the world’s largest fireworks display (2019) di如图，△ABC的顶点A、B、C均在⊙O上，若∠ABC+∠AOC=87°，则∠AOC的大小是_____． 58° 【解析】试题解析：∵∠ABC=∠AOC， 而∠ABC+∠AOC=90°， ∴∠AOC+∠AOC=90°， ∴∠AOC=60°．