如图，C地在A地的正东方向，因有大山阻隔，由A地到C地需绕行B地，已知B地位于A地北偏东67°方向，距离A地520km，C地位于B地南偏东30°方向，若打通穿山隧道，建成两地直达高铁，求A地到C地之间高铁线路的长．（结果保留整数）

（参考数据：sin67°≈ $\frac{12}{13}$ ，cos67°≈ $\frac{5}{13}$ ，tan67°≈ $\frac{12}{5}$ ， $\sqrt{3}$ ≈1.73）

    London is one of the most popular sites in the world for tourists to visit.If you are planning a trip to London in the future,you're lucky.There are a variety of attractions for you to enjoy.

    One of the most popular tourist attractions in London is the Tower of London.Founded more than 900 years ago, the Tower of London is one of the world's most famous towers and has changed a lot.Here,you can also find the seven ravens（乌鸦）which live in the Tower.There is a story that says: If there are no ravens in the Tower, the Tower and the kingdom will fall.There are also lots of tours,exhibits.and special events that you can enjoy throughout the year.

    Another popular place to visit is Westminster Abbey.It was set up in 1065 by Edward the Confessor.Visitors to Westminster Abbey can enjoy its beautiful special Gothic architecture（哥特式建筑）.There are also lots of memorials of Kings and Queens to enjoy.Excellent transportation is available here by bus or tube from many locations in London.

    Buckingham Palace is another place with a rich history to discover.It's the official London residence（住处）of Queen ElizabethⅡ.During August and September,you can visit the State Rooms and see the Changing of the Guards.The Queen's Gallery is open to the public daily.Checking the official timetable before you make sure to visit the Palace is a must,because it is not open year round.