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The given figure shows a pentagon ABCDE. EG drawn parallel to DA meets BA produced at G and CF draw parallel to DB meets AB produced at F. - Mathematics

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Question

The given figure shows a pentagon ABCDE. EG drawn parallel to DA meets BA produced at G and CF draw parallel to DB meets AB produced at F.

Prove that the area of pentagon ABCDE is equal to the area of triangle GDF.

Sum
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Solution


Since triangle EDG and EGA are on the same base EG and between the same parallel lines EG and DA.

Therefore,

A(ΔEDG) = A(ΔEGA)

Subtracting ΔEOG from both sides, we have

A(ΔEOD) = A(ΔGOA)              ...(i)

Similarly,

A(ΔDPC) = A(ΔBPF)              ...(ii)

Now

A(ΔGDF) = A(ΔGOA) + A(ΔBPF) + A(pen. ABPDO) 

= A(ΔEOD) + A(ΔDPC) + A(pen. ABPDO)

= A(pen. ABCDE)

Hence, proved.

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Figures Between the Same Parallels
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Chapter 16: Area Theorems [Proof and Use] - Exercise 16 (A) [Page 197]

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Selina Concise Mathematics [English] Class 9 ICSE
Chapter 16 Area Theorems [Proof and Use]
Exercise 16 (A) | Q 8 | Page 197
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