src.c: In function 'main':
src.c:11:57: error: 'c1' undeclared (first use in this function)
printf("C1=%.2f\nSa=%.2f\nSb=%.2f\nVa=%.2f\nVb=%.2f\n",c1,Sa,Sb,Va,Vb);
^
src.c:11:57: note: each undeclared identifier is reported only once for each function it appears in