View Compilation Error

0_0_39727061_28311.cpp: In function 'int main()':
0_0_39727061_28311.cpp:4:12: error: 'acos' was not declared in this scope
    4 | #define PI acos(-1)
      |            ^~~~
0_0_39727061_28311.cpp:14:53: note: in expansion of macro 'PI'
   14 |                 ans = (n - 1)*(r*r*sin((180.0 / n)*(PI / 180.0))*cos((180.0 / n)*(PI / 180.0))) + r*r*sin((180.0 / n)*(PI / 180.0));//度数乘以pi/180
      |                                                     ^~
0_0_39727061_28311.cpp:14:36: error: 'sin' was not declared in this scope
   14 |                 ans = (n - 1)*(r*r*sin((180.0 / n)*(PI / 180.0))*cos((180.0 / n)*(PI / 180.0))) + r*r*sin((180.0 / n)*(PI / 180.0));//度数乘以pi/180
      |                                    ^~~
0_0_39727061_28311.cpp:14:66: error: 'cos' was not declared in this scope
   14 |                 ans = (n - 1)*(r*r*sin((180.0 / n)*(PI / 180.0))*cos((180.0 / n)*(PI / 180.0))) + r*r*sin((180.0 / n)*(PI / 180.0));//度数乘以pi/180
      |                                                                  ^~~