alternate angle
noun [ C, usually plural ] mathematics UK specialized uk/ɒlˌtɜː.nət ˈæŋ.ɡəl/ us/ˈɑːltɝː.nət ˌæŋ.ɡəl/ (US alternate angle)
错角，交错角（交错角是两个相等的角之一：平行的两条线被第三条直线所截，这第三条直线的两侧就形成两个相等的交错角，两条平行线的两侧也各形成两个交错角）
one of two equal angles on opposite sides of a line that crosses two usually parallel lines (= lines that are always the same distance apart), and on opposite sides of those lines
Compare: corresponding angle