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BOnd 10 minute tests 10-11 Test 7
Posted: Sun Aug 02, 2009 4:57 pm
by yoyo123
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
)
Re: BOnd 10 minute tests 10-11 Test 7
Posted: Sun Aug 02, 2009 7:42 pm
by wiltsman
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
)
You must be looking at the wrong answer set; in my book, the answer is A) 4x^2 (which is correct).
Posted: Sun Aug 02, 2009 7:52 pm
by yoyo123
Yes
looking at the squares does x=2y?
It is so long since I have done shape at this level
Posted: Sun Aug 02, 2009 8:01 pm
by wiltsman
yoyo123 wrote:Yes
looking at the squares does x=2y?
It is so long since I have done shape at this level
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.
Posted: Sun Aug 02, 2009 9:22 pm
by yoyo123
Thank you so much..
Brilliant explanation..
