a + b = 180; b + c = 204; a + c = 186
=> (a + b) + (b + c) + (a + c) = 180 + 204 + 186
=> a + b + b + c + a + c= 570
=> 2 x (a + b + c) = 570
=> a + b + c = 570 : 2
=> a + b + c = 285
=> a = 285 - 204 = 81
=> b = 180 - 81 = 99
=> c = 285 - 81 - 99 = 105
A + B = 180 ; B + C = 204 ; A + C = 186
A + C - A - B = 186 - 180 = 6
C - A= 6
Vậy C = (204 + 6)/2 = 105
B = 204 - 105 = 99
A = 186 - 105 = 81
Vậy A = 81 ; B = 99 ; C = 105