0938132人目の素数さん
2018/06/04(月) 20:16:35.13ID:tzM+Pvvjいいえ。
外接円の半径を R とすると
AB = 2R sin(∠AOB/2),
BC = 2R sin(∠BOC/2),
CD = 2R sin(∠COD/2),
DA = 2R sin(∠DOA/2),
また題意より
R = 65/8,
BC = CD = 13,
AB+BC+CD+DA = 44,
したがって
AB + DA = 44 -13 -13 = 18,
∠AOB/2 = 2arctan(4/7) = arcsin(56/65) = 59.4897626゚
∠BOC/2 = 2arctan(1/2) = arcsin(4/5) = 53.130102゚
∠COD/2 = 2arctan(1/2) = arcsin(4/5) = 53.130102゚
∠DOA/2 = 2arctan(1/8) = arcsin(16/65) = 14.25003゚
よって
AB = 14
DA = 4