yī / tiáo / zhí / xiàn / xíng / chéng / de / jiǎo / jiù / shì / píng / jiǎo / dà / xiǎo / wéi / yī / bǎi / bā / shí / dù

一条直线形成的角就是平角，大小为一百八十度。

An angle formed by a straight line is a straight angle, measuring 180 degrees.