Intercept theorem
ON RATIOS OF LINE SEGMENTS FORMED WHEN 2 INTERSECTING LINES ARE CUT BY A PAIR OF PARALLELS
Basic proportionality theorem; Intercept thm; Side splitter theorem; Basic Proportionality Theorem
The intercept theorem, also known as Thales's theorem, basic proportionality theorem or side splitter theorem is an important theorem in elementary geometry about the ratios of various line segments that are created if two intersecting lines are intercepted by a pair of parallels. It is equivalent to the theorem about ratios in similar triangles.