View Compilation Error

0_0_30476040_4039.cpp: In function 'int main()':
0_0_30476040_4039.cpp:48:205: error: 'l' was not declared in this scope
         printf("Case #%d: %.4f\n",Casee,sqrt(sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3))*sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3))-sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3))*sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3))/4.0)+2*l*asin(sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3))/2.0/l));
                                                                                                                                                                                                             ^