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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.
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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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