A.\(A = \left| {{A_1} - {A_2}} \right|.\)
B.\(A \le {A_1} + {A_2}.\)
C.\(\left| {{A_1} - {A_2}} \right| \le A \le {A_1} + {A_2}.\)
D.\(A \ge \left| {{A_1} - {A_2}} \right|.\)