please help... I dont know how to that

in this code I try to perform number of commands;

first getting tow points from the user.one represent the center of a circle and the other represent a point on the same circle.

then I must use 4 functions . and then to print on the screen these solutions:

r=radius d=diameter , c=circumference a= area. t

I have many bugs but I have no clue how to solve it , thanks for the helpers.

Code:double distance(double x1, double x2, double y1, double y2) { double a=0 ,b=0 ,c=0, d=0 ,e=0 ; a= x2 -x1; b= y2 -y1; c = a*a; d = b*b; e=c+d; return sqrt(e); } double radius(double r_x1, double r_y1, double r_x2, double r_y2) { double r =0; r = distance(r_x1, r_x2, r_y1, r_y2); return r; } double circumference(double r) { double pai=3.1416, circ=0; r = distance; circ = rad * pai * 2; return circ; } double area(double r) { double rad = distance, pai =3.1416, c=0; r = rad*rad*pai; return r; } int main() { double x1=0, x2=0, y1=0, y2=0, D=0; printf("please enter tow points:\n"); scanf("%g %g %g %g", &x1, &y1, &x2,&y2); D = distance(x1,x2,y1,y2) * 2; printf("R = %g \n ",distance(x1,x2,y1,y2)); printf("D = %g \n" , 2* distance(x1,x2,y1,y2)); printf("C = %g \n ",circ(r)); printf("A = %g \n", area r)); return 0; }