View Compilation Error

0_0_37905753_24865.cpp: In function 'int main()':
0_0_37905753_24865.cpp:63:8: error: 'd2' was not declared in this scope
   A=a1*d2+a2*d1;
        ^
0_0_37905753_24865.cpp:63:14: error: 'd1' was not declared in this scope
   A=a1*d2+a2*d1;
              ^