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I tried with checking similarity of triangles ABC - DBE and ABC - FEC. But couldn't deduce lengths of DE and EF, only came to ratio of BE/DB to be 5/7. Can anyone post a solution on how to approach such questions?

Thanks in advance!
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angle DBC=angle ACB=angle DEB= angle FEC
Hence DB=DE and FE=FC
Perimeter of ADEF= AD+DE+FE+AF=AD+DB+FC+AF=AB+AC=28+28=56
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Please kudos if this helped.
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I tried with checking similarity of triangles ABC - DBE and ABC - FEC. But couldn't deduce lengths of DE and EF, only came to ratio of BE/DB to be 5/7. Can anyone post a solution on how to approach such questions?

Thanks in advance!

By similarity, ABC, BDE & CEF are all isosceles triangles

So \(AB=AC\), \(BD=DE\) & \(EF=CF\) and from parallelogram, \(AD=EF\), \(DE=AF(=BD)\)

Perimeter of parallelogram ADEF = \(AD+DE+EF+AF = AD+BD+AD+BD\)

We know that \(AD+BD = AB = 28\)

So \(Permieter = AB+AB = 28+28= 56\)

(C)

Kudos if this helped !


Dear firas92,

Sorry to sound so dumb but could you please shed some light on the highlighted part as I fail to grasp the logic.

Many thanks
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nigina93
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I tried with checking similarity of triangles ABC - DBE and ABC - FEC. But couldn't deduce lengths of DE and EF, only came to ratio of BE/DB to be 5/7. Can anyone post a solution on how to approach such questions?

Thanks in advance!

By similarity, ABC, BDE & CEF are all isosceles triangles

So \(AB=AC\), \(BD=DE\) & \(EF=CF\) and from parallelogram, \(AD=EF\), \(DE=AF(=BD)\)

Perimeter of parallelogram ADEF = \(AD+DE+EF+AF = AD+BD+AD+BD\)

We know that \(AD+BD = AB = 28\)

So \(Permieter = AB+AB = 28+28= 56\)

(C)

Kudos if this helped !


Dear firas92,

Sorry to sound so dumb but could you please shed some light on the highlighted part as I fail to grasp the logic.

Many thanks

It is a property of parallelograms to have equal opposite sides.

Since ADEF is a parallelogram, its opposite sides will be equal. That is, AD=EF and DE=AF

The perimeter of any quadrilateral can be calculated as the sum of the lengths of its edges.

So perimeter of Parallelogram ADEF = AD+DE+EF+AF

Hope it is clear
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