Triangle def is isosceles, angle d is the vertex angle, de=x+7, df=3x-1, and ef=2x+5

The three sides of isosceles triangle are DE = DF = 11 unit , and EF = 13 unit

Step-by-step explanation:

Given as :

DEF is a isosceles Triangle , with vertex D

The three sides is as

DE = x + 7

DF = 3x - 1

EF = 2x + 5

∵ DEF is an isosceles triangle then two of its sides must be equal

So , Let DE = DF

Or,     x + 7 = 3x - 1

Or,      7 + 1 = 3x - x

Or,            8 = 2x

∴               x = 4

So, The measure three sides of isosceles Triangle are :

DE = x + 7 = 4 + 7 = 11   unit  

DF = 3x - 1 = 3×(4) - 1 = 11   unit

EF = 2x + 5 = 2×(4) + 5 = 13   unit

Hence The three sides of isosceles triangle are DE = DF = 11 unit ,  and EF = 13 unit    Answer

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step-by-step explanation: