Areas of Parallelograms and Triangles

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Homework Help Overview

The discussion revolves around the areas of two equilateral triangles, ABC and BDE, with specific geometric relationships and conditions, including the midpoint of a side and intersections of lines. The participants are tasked with demonstrating various area relationships between these triangles.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationships between the areas of the triangles and consider hints about geometric constructions, such as joining points and establishing parallel lines. There is also a focus on the formula for the area of an equilateral triangle.

Discussion Status

Some participants have provided hints and shared their attempts, while others express uncertainty about their diagrams and calculations. There is acknowledgment of correct interpretations, but no consensus or complete solutions have been reached.

Contextual Notes

Participants mention difficulties in visualizing the problem without a diagram and refer to specific geometric properties and relationships that need to be clarified or confirmed.

agnibho
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Homework Statement


ABC and BDE are two equilateral triangles such that D is the midpoint of BC. If AE intersects BC at F, show that :-
(i) ar(BDE) = 1/4 ar(ABC)
(ii) ar(BDE) = 1/2 ar(BAE)
(iii) ar(ABC) = 2ar(BEC)
(iv) ar(BFE) = ar(AFD)
(v) ar(BFE) = 2ar(FED)
(vi) ar(FED) = 1/2ar(AFC)


Homework Equations





The Attempt at a Solution


There was this hint :- [join EC and AD and then showing BE ll AC and DE ll AB,etc.]
 
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I couldn't upload the diagram.
I tried to follow the hint but from there on I couldn't succeed in solving this sum.
If anyone would tell me how to do this sum I'll be pleased
 
agnibho said:
ABC and BDE are two equilateral triangles such that D is the midpoint of BC. If AE intersects BC at F, show that :-
(i) ar(BDE) = 1/4 ar(ABC)
(ii) ar(BDE) = 1/2 ar(BAE)
(iii) ar(ABC) = 2ar(BEC)
(iv) ar(BFE) = ar(AFD)
(v) ar(BFE) = 2ar(FED)
(vi) ar(FED) = 1/2ar(AFC)

There was this hint :- [join EC and AD and then showing BE ll AC and DE ll AB,etc.]

My take on your diagram attached.
To continue, what is the formula for the area of an equilateral triangle?
 

Attachments

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Area of an equilateral triangle = [tex]\sqrt{}3[/tex]/4*side2
 
agnibho said:
Area of an equilateral triangle = [tex]\sqrt{}3[/tex]/4*side2

I assume my diagram was correct?

Anyway, D is at the midpoint of BC, so BD = BC/2
Aabc = [tex]\sqrt{}3[/tex]/4*BC2
Abde = [tex]\sqrt{}3[/tex]/4*BD2 = [tex]\sqrt{}3[/tex]/4*(BC/2)2

Finish that and retry the others.
 
Yes your diagram was correct
 
Thanks for your help.
 

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