面白い問題おしえて〜な 37問目

>>943-944
O (0, 0)
A (sin(C-B), cos(C-B))
B (-sin(A), -cos(A))
C (sin(A), -cos(A))
I (sin(C)-sin(B), cos(B)+cos(C)-1)
H (sin(C-B), 2cos(B)cos(C)-cos(A)) = 3G,

OI = R√{3 -2cos(A) -2cos(B) -2cos(C)},
OH = R√{3 +2cos(2A) +2cos(2B) +2cos(2C)} = 3OG,