You have to use thales theorem, thales corollay, and their converses as well as find the ratio using them. Please give statement/reasoning proof
in Geometry Answers by

Your answer

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
To avoid this verification in future, please log in or register.

1 Answer

The diagonal splits the trapezoid into two triangles ACD and ABC.

MN creates two pairs of similar triangles: AMP and ACD, and CNP and ABC.

Thales' Theorem (one of several) concerns the proportionality of the sides of similar triangles. Applying it, we get:

Let AD=8x, then AM=3x and DM=5x, AD=8x, because AM/AD=3/8=AP/AC (Thales);

let AC=8y, then AP=3y and CP=5y, because of similar triangles AMP and ACD.

CP/AC=5/8=CN/BC, because of similar triangles CNP and ABC.

If BC=8z, then CN=5z and BN=3z, making BC/BN=8/3, or BC:BN=8:3.

The corollary to this is that a line (l in this case) parallel to the parallel sides of a trapezoid, creating two similar trapezoids, also creates equal proportionalities in the sloping sides, because the diagonal divides the trapezoid into two triangles which are not generally similar but nevertheless share corresponding proportionalities: AM:MD=BN:NC, for example.

by Top Rated User (1.2m points)

Related questions

1 answer
asked Aug 27, 2014 in Geometry Answers by anonymous | 814 views
1 answer
1 answer
asked Jun 27, 2017 in Geometry Answers by Natasha Butcher | 640 views
Welcome to MathHomeworkAnswers.org, where students, teachers and math enthusiasts can ask and answer any math question. Get help and answers to any math problem including algebra, trigonometry, geometry, calculus, trigonometry, fractions, solving expression, simplifying expressions and more. Get answers to math questions. Help is always 100% free!
87,516 questions
100,279 answers
2,420 comments
732,335 users