(一)复习要点1郾比例线段(1)在两条线段的比a∶b中,a叫做比的项,b叫做比的项郾(2)在四条线段中,如果其中两条线段的比等于另外两条线段的比,那么这四条线段叫做线段郾(3)如果a∶b=c∶d,那么, 叫做比例外项,,叫做比例内项,d叫做a,b,c的第比例项郾(4)如果a∶b=b∶c,那么线段叫 (1) Review point 1 Proportional line segment (1) In the ratio a:b of two line segments, a is called the ratio term, b is called the ratio term (2) in four line segments, if the ratio of two line segments is Equal to the ratio of the other two segments, then the four segments are called segment 郾 (3) If a:b=c:d, then, it is called the proportional external term, which is called the proportional internal term, and d is the proportional proportion of a, b, and c. Item (4) If a:b=b:c, then the line segment is