SA3 marksYear: 2023HardCBSE Class 10
trianglessimilarityparallelogramproof
Question
In the given figure, ABCD is a parallelogram. BE bisects CD at M and intersects AC at L. Prove that EL=2BL.

Solution
1
△ALE∼△CLB (AA similarity)
⇒CLAL=BLEL ... (i)
+1 mark2
Also △CLM∼△ALB (AA similarity)
⇒CLAL=CMAB
+1 mark3
Since AB=CD (parallelogram) and CM=2CD (M is midpoint): CLAL=CD/2CD=2 ... (ii)
+0.5 marks4
From (i) and (ii): BLEL=2⇒EL=2BL
+0.5 marks