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E, F, G, and H Are the Midpoints of the Sides of a Parallelogram Abcd. Show that the Area of Quadrilateral Efgh is Half of the Area of Parallelogram Abcd. - Mathematics

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Question

E, F, G, and H are the midpoints of the sides of a parallelogram ABCD.
Show that the area of quadrilateral EFGH is half of the area of parallelogram ABCD.

Sum

Solution

Join HF.

Since H and F are mid-points of AD and BC respectively,
∴ AH = `1/2 "AD and BF" = 1/2 "BC"`

Now, ABCD is a parallelogram.
⇒ AD = BC and AD ∥ BC

⇒ `1/2 "AD" = 1/2`BC and AD || BC

⇒ AH = BF and AH ∥ BF
⇒ ABFH is a parallelogram.

Since parallelogram FHAB and ΔFHE are on the same base FH and between the same parallels HF and AB,
A( ΔFHE ) = `1/2`A ( ||m FHAB )     .....(i)

Similarly,
A( ΔFHG ) = `1/2`A ( ||m FHDC )    .......(ii)

Adding (i) and (ii), We get,
A( ΔFHE ) + A( ΔFHG ) = `1/2 "A"( ||^m "FHAB" ) + 1/2`A ( ||m FHDC ) 
⇒ A( EFGH ) = `1/2`[ A ( ||m FHAB ) + A ( ||m FHDC ) ]

⇒ A( EFGH ) = `1/2`A( ||m ABCD )

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Figures Between the Same Parallels
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Chapter 16: Area Theorems [Proof and Use] - Exercise 16 (C) [Page 202]

APPEARS IN

Selina Concise Mathematics [English] Class 9 ICSE
Chapter 16 Area Theorems [Proof and Use]
Exercise 16 (C) | Q 10 | Page 202
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