这不是特殊角的数值。用计算噐计算得出该角为 arccos(√2/3)=61.87°
经计算器计算精确值为61.87449
cos(x)=√2/3x=ArcCos(√2/3)=1.0799136485055852506504128103829119960996575407886...=61.874494297944293908702166372228836034797600213877...°
