View Compilation Error

0_0_2718289_31098.c:2:10: #include expects "FILENAME" or <FILENAME>
0_0_2718289_31098.c: In function `main':
0_0_2718289_31098.c:7: error: `PI' undeclared (first use in this function)
0_0_2718289_31098.c:7: error: (Each undeclared identifier is reported only once
0_0_2718289_31098.c:7: error: for each function it appears in.)