View Compilation Error

555423_0_0_22650.cpp:1: error: expected constructor, destructor, or type conversion before '<' token
555423_0_0_22650.cpp:1: error: expected `,' or `;' before '<' token
555423_0_0_22650.cpp: In function `int main()':
555423_0_0_22650.cpp:7: error: `scanf' undeclared (first use this function)
555423_0_0_22650.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
555423_0_0_22650.cpp:11: error: `sqrt' undeclared (first use this function)
555423_0_0_22650.cpp:14: error: `acos' undeclared (first use this function)
555423_0_0_22650.cpp:14: error: `printf' undeclared (first use this function)