[计] angle of first pie slice, angle of first slice

dì yī shàn qū qǐ shǐ jiǎo dù ㄉㄧˋ ㄧ ㄕㄢˋ ㄑㄩ ㄑㄧˇ ㄕˇ ㄐㄧㄠˇ ㄉㄨˋ