View Compilation Error

0_0_32829055_23256.cpp:3:26: error: 'acos' was not declared in this scope
 const double PI = acos(-1);
                          ^
0_0_32829055_23256.cpp: In function 'double dist(circle, circle)':
0_0_32829055_23256.cpp:11:56: error: 'sqrt' was not declared in this scope
     return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
                                                        ^
0_0_32829055_23256.cpp: In function 'double area(circle, circle)':
0_0_32829055_23256.cpp:14:34: error: 'min' was not declared in this scope
        if((dist(a, b)+min(a.r,b.r))<=max(a.r,b.r))
                                  ^
0_0_32829055_23256.cpp:14:49: error: 'max' was not declared in this scope
        if((dist(a, b)+min(a.r,b.r))<=max(a.r,b.r))
                                                 ^
0_0_32829055_23256.cpp:26:76: error: 'acos' was not declared in this scope
             double d1=2*acos((a.r*a.r+length*length-b.r*b.r)/(2*a.r*length));
                                                                            ^
0_0_32829055_23256.cpp:28:53: error: 'sin' was not declared in this scope
             double area1=a.r*a.r*d1/2-a.r*a.r*sin(d1)/2;
                                                     ^