View Compilation Error

0_0_38820159_29493.cpp:16:17: error: 'acos' was not declared in this scope
   16 | const double pi=acos(-1);
      |                 ^~~~
0_0_38820159_29493.cpp: In function 'void solve()':
0_0_38820159_29493.cpp:30:34: error: 'sqrt' was not declared in this scope
   30 |                         double d=sqrt(dis);
      |                                  ^~~~
0_0_38820159_29493.cpp:31:34: error: 'acos' was not declared in this scope
   31 |                         double a=acos(change(R,d,r))*2;
      |                                  ^~~~