∡CAO=90°
∡CBO=90°
∡ABO=∡BAO=40°
Yгол BOA
∡BOA=180°-2·∡ABO
∡BOA=180°-2·40°
∡BOA=180°-80°
∡BOA=100°
Yгол ACB
∡ACB=360°-(∡BOA+∡CAO+∡CBO)
∡ACB=360°-(100°+2·90°)
∡ACB=360°-(100°+180°)
∡ACB=360°-280°
∡ACB=80°
ответ: 80°
∡CAO=90°
∡CBO=90°
∡ABO=∡BAO=40°
Yгол BOA
∡BOA=180°-2·∡ABO
∡BOA=180°-2·40°
∡BOA=180°-80°
∡BOA=100°
Yгол ACB
∡ACB=360°-(∡BOA+∡CAO+∡CBO)
∡ACB=360°-(100°+2·90°)
∡ACB=360°-(100°+180°)
∡ACB=360°-280°
∡ACB=80°
ответ: 80°