1) HF = FK + KH
HF = 12 + 8 =20(см)
2) (x + 13) + x =73
2x + 13 = 73
2x = 73 - 13
2x = 60
x = 30
30 + 13 = 43
Ответ: ac =43, bc = 30
3) x + (x+38) = 180
2x + 38 = 180
2x = 180 - 38
2x = 142
x = 71
71 + 38 = 109
Ответ: первый угол = 71, а второй = 109