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Math Help - help!!pythogras in trapizium

  1. #1
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    help!!pythogras in trapizium

    http://www.emaths.co.uk/sats/2009/2009_68_Paper2.pdf < pls go to this link and go question 24 help me solve it plese
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  2. #2
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    Quote Originally Posted by coolubi View Post
    http://www.emaths.co.uk/sats/2009/2009_68_Paper2.pdf < pls go to this link and go question 24 help me solve it plese
    Draw a line parallel to the 20cm side, at the other end, where the kcm side meets the 22cm side, straight down onto the 30cm side.

    You now have a rectangle and right-angled triangle.

    The sides of this triangle are 22cm, 20cm and (30-k)cm.

    To use Pythagoras theorem, the triangle must be right-angled, as this one is.
    The sum of the squares of the two shorter sides is the square of the longest side, the hypotenuse.

    Then, your formula is 20^2+(30-k)^2=22^2

    20(20)+(30-k)(30-k)=22(22)

    Multiply this out and write the quadratic equation for k.
    K is positive, so find the positive answer for k, when you solve the quadratic, by factorising it after bringing all terms to one side, making it =0,
    or using the quadratic formula.
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