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ABC is a triang D is a point on AB such that AD = 14 AB and E is a point on AC such that AE = 14 AC. Prove that DE = 14 BC.

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Question

ABC is a triang D is a point on AB such that AD = `1/4` AB and E is a point on AC such that AE = `1/4` AC. Prove that DE = `1/4` BC.

Sum
Theorem
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Solution

Let P and Q be the midpoints of AB and AC respectively.

Then PQ || BC such that

PQ = `1/2` BC         ......(i)

In ΔAPQ, D and E are the midpoint of AP and AQ are respectively

∴ DE || PQ and DE = `1/2` PQ       ....(ii)

From (1) and (2)   DE = `1/2 PQ = 1/2 PQ =  1/2  (1/2 BC) `    

DE = `1 /4`BC

Hence, proved.

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Chapter 13: Quadrilaterals - Exercise 13.4 [Page 64]

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R.D. Sharma Mathematics [English] Class 9
Chapter 13 Quadrilaterals
Exercise 13.4 | Q 16 | Page 64

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