CBSE NCERT Solutions Chapter 6 Triangles Exercise 6.2 Question 9
9. ABCD is a trapezium in which AB DC and its diagonals intersects each other at the point O. Show that
Construction: Draw line EF passing through O parallel to AB. A line parallel to AB is also parallel to DC.
Proof: In ADC, EO DC.
Therefore, by Basic Proportionality Theorem, we get (1)
In ABD, EO AB.
Therefore, by Basic Proportionality Theorem, we get (2)
Therefore, from (1) and (2), we get