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PostPosted: Sun Aug 02, 2009 3:57 pm 
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Joined: Mon Jun 18, 2007 2:32 pm
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Location: East Kent
Can you help.. I have stared at this for ages!

Test 7 question 4

a hexagon ( not regular) with 2 shorter sides x and 4 longer sides y

What is correct formula for the area. Answer is 1/2 xy

can you help with a simple explanation why?


(sunday afternoon and I am brain dead :oops:)


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PostPosted: Sun Aug 02, 2009 6:42 pm 
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Joined: Fri Mar 20, 2009 7:34 pm
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yoyo123 wrote:
Can you help.. I have stared at this for ages!

Test 7 question 4

a hexagon ( not regular) with 2 shorter sides x and 4 longer sides y

What is correct formula for the area. Answer is 1/2 xy

can you help with a simple explanation why?


(sunday afternoon and I am brain dead :oops:)


You must be looking at the wrong answer set; in my book, the answer is A) 4x^2 (which is correct).


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PostPosted: Sun Aug 02, 2009 6:52 pm 
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Joined: Mon Jun 18, 2007 2:32 pm
Posts: 6966
Location: East Kent
Yes :oops:

looking at the squares does x=2y?

It is so long since I have done shape at this level :oops:


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PostPosted: Sun Aug 02, 2009 7:01 pm 
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Joined: Fri Mar 20, 2009 7:34 pm
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yoyo123 wrote:
Yes :oops:

looking at the squares does x=2y?

It is so long since I have done shape at this level :oops:


No, x != 2y.

If you can't see how to do it, read on:

The shape is made up of a central rectangle, with congruent triangles to the left and right.

The diagram is drawn on a squared background and we can see that x = 4 squares. The height of the hexagon is 8 squares (= 2x) so the area of the central rectangle = 2x * x = 2x^2.

The width of each triangle is 4 squares = x, so the area of each triangle = 0.5bh = 0.5 * x * 2x = x^2. There are 2 triangles so they contribute 2x^2 to the whole area, and adding the area of the central rectangle, we get 2x^2 + 2x^2 = 4x^2.


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PostPosted: Sun Aug 02, 2009 8:22 pm 
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Joined: Mon Jun 18, 2007 2:32 pm
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Location: East Kent
Thank you so much..

Brilliant explanation..

:D


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