View Compilation Error

0_0_39129656_9920.cpp: In function 'int main()':
0_0_39129656_9920.cpp:26:32: error: 'acos' was not declared in this scope
   26 |                         s[i] = acos(-1) * ri * ri;
      |                                ^~~~
0_0_39129656_9920.cpp:30:24: error: 'fabs' was not declared in this scope; did you mean 'labs'?
   30 |                 while (fabs(r-l)>0.0000001)
      |                        ^~~~
      |                        labs