题目

Every foreign student who has been accepted to study in this country must have a legal document called a visa from the United States government. A visa permits a foreign citizen to travel to the United States and request permission to enter the country. The rules for getting a visa can be found on the State Department Web site. The address is unitedstatesvisas. gov. Unitedstatesvisas is all one word. Another State Department Web site for students from other countries is educationusa. gov. If you are requesting a visa for the first time, you may have to appear at the American Embassy in your co设的内角A、B、C、所对的边分别为a、b、c，已知    （Ⅰ）求的周长;（Ⅱ）求的值.