View Compilation Error

0_0_15577591_15456.cpp: In function 'double calArea(Circle, Circle)':
0_0_15577591_15456.cpp:11:59: error: 'sqrt' was not declared in this scope
     d=sqrt((c1.x-c2.x)*(c1.x-c2.x)+(c1.y-c2.y)*(c1.y-c2.y));
                                                           ^
0_0_15577591_15456.cpp:15:25: error: 'acos' was not declared in this scope
         return acos(-1.0)*c2.r*c2.r;
                         ^
0_0_15577591_15456.cpp:17:25: error: 'acos' was not declared in this scope
         return acos(-1.0)*c1.r*c1.r;
                         ^
0_0_15577591_15456.cpp:19:53: error: 'acos' was not declared in this scope
     angle1=acos((c1.r*c1.r+d*d-c2.r*c2.r)/(2*c1.r*d));
                                                     ^
0_0_15577591_15456.cpp:23:25: error: 'sin' was not declared in this scope
     s3=c1.r*d*sin(angle1);
                         ^