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    (Original post by TerraformingYou)
    I just came here to ask, is a square a rhombus? Or are they "mutually exclusive" shapes? Because I proved ABCD, that is already KNOWN as a parallelogram, is a rhombus by proving that AC is perpendicular to BD. This is a valid method, right? Since the only two shapes that have their diagonals perpendicular are rhombuses and kites, right? And since ABCD is a parallelogram, then ABCD MUST be a rhombus, right?

    People have been telling me that a square is not a rhombus and it's driving me crazy.. Even if it IS a square, all the question asks is to prove that ABCD is a rhombus, so even if ABCD IS a square, a square is a rhombus, right?

    I'm going bonkers, I apologise..
    Any shape with four sides is a parallelogram which includes square.

    AC can not be perpendicular to BD. Though I didn't do it, rhombus actually has no 90 degree angles so we have to use dot product to show that the two direction vectors aren't equal to 0. I just proved the lengths are equal which should give one mark and finding OD would be another 1 or 2 marks.
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    (Original post by Devillain)
    Yep. And I can remember 2.5 and 0.644 as well... Only thing being that I wrote 0.65 (I hate significant figures )
    They asked us to show it to two decimal places so you are right. Rejoice
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    Question paper: http://justpastpapers.com/wp-content.../Scan20001.pdf

    Answers: http://justpastpapers.com/9709paper32-answers/
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    (Original post by Coloneltreavy)
    Any shape with four sides is a parallelogram which includes square.

    AC can not be perpendicular to BD. Though I didn't do it, rhombus actually has no 90 degree angles so we have to use dot product to show that the two direction vectors aren't equal to 0. I just proved the lengths are equal which should give one mark and finding OD would be another 1 or 2 marks.
    AC and BD are the diagonals of the quadrilateral; proving that the diagonals in the parallelogram (you know what I'm talking about, right?) are equal makes it a rhombus, no?

    EDIT: The diagonals I'm talking about don't mean the sides of the quadrilateral, but the two lines in the quadrilateral you can make through two opposite points in that quadrilateral..
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    (Original post by TerraformingYou)
    AC and BD are the diagonals of the quadrilateral; proving that the diagonals in the parallelogram (you know what I'm talking about, right?) are equal makes it a rhombus, no?

    EDIT: The diagonals I'm talking about don't mean the sides of the quadrilateral, but the two lines in the quadrilateral you can make through two opposite points in that quadrilateral..
    Yea I get what you mean. But the diagonals can also prove it to be a square. What we need to do is to distinguish from a square.
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    (Original post by Coloneltreavy)
    Yea I get what you mean. But the diagonals can also prove it to be a square. What we need to do is to distinguish from a square.
    A square is a rhombus (I searched), and so it doesn't matter if it's a square or not.. And parallelograms cannot be kites..
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    what about statistics 72 (CIE) ? do you know any forum or page where I could find/discuss the answers?
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    (Original post by Rcnl)
    what about statistics 72 (CIE) ? do you know any forum or page where I could find/discuss the answers?
    http://www.thestudentroom.co.uk/foru...p?f=373&page=3

    ^you may be able to find a thread relevant to your needs over here. CIE ones are quite rare though.
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    I felt it was a bit harder, hoping for a mid 50 treshold. Do you guys remember you answers?
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    (Original post by Vuceee)
    I felt it was a bit harder, hoping for a mid 50 treshold. Do you guys remember you answers?
    it was actually a little harder. the real problem was, average/above-average kids could easily ace it if we had more time. only the math whizzes had a good exam, majority people i know, both good and bad at math, either had a so-so or a bad exam. a lot of kids could not even finish. so hoping the threshold is lowered, i don't think it will be above 60 cause I did June 2015 (32) and it was easier and had a threshold at 58 or sth for an A
 
 
 
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