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D, E, and F are the mid-points of the sides AB, BC and CA of an isosceles ΔABC in which AB = BC. Prove that ΔDEF is also isosceles. - Mathematics

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Question

D, E, and F are the mid-points of the sides AB, BC and CA of an isosceles ΔABC in which AB = BC.

Prove that ΔDEF is also isosceles.

Sum

Solution

DF = `1/2`BC          ...(i)

DE = `1/2`AC        ...(ii)

EF = `1/2`AB       

EF = `1/2`BC        ...(iii)       ...[AB = BC]

From equation (i) & (ii)

DF = EF

Hence, DEF is also isosceles triangle. 

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Chapter 12: Mid-point and Its Converse [ Including Intercept Theorem] - Exercise 12 (A) [Page 150]

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Selina Concise Mathematics [English] Class 9 ICSE
Chapter 12 Mid-point and Its Converse [ Including Intercept Theorem]
Exercise 12 (A) | Q 3 | Page 150

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