【数セミ】エレガントな解答をもとむ3【2018.10】

[0815 １３２人目の素数さん 2020/11/14(土) 21:30:06.74 ID:MWjdA7m9]

>>812
面積で表わすなら
�僊｡B｡C。= (1/2)(2R)^2 sin(A｡)sin(B｡)sin(C｡)
　= (1/2){sin(A｡)cos(A｡)BC^2 + sin(B)cos(B｡)CA^2 + sin(C｡)cos(C｡)AB^2 ± 4S'},
　S' = S(a' ,b', c')
かな