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    Really stuck with this 1 mark question ...

    A circle with centre C (-5,6) touches the y axis as shown in the diagram

    Find the equation of the circle in the form
    (x-a)^2 + (y-b)^2 = r^2

    i found that out ... (x+5)^2 + (y-6)^2 = 5,

    BUT the next question says verify that the point P (-2,2) lies on the circle

    i dont know how to work it out help pl0x
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      (Original post by Skaterkid)
      Really stuck with this 1 mark question ...

      A circle with centre C (-5,6) touches the y axis as shown in the diagram

      Find the equation of the circle in the form
      (x-a)^2 + (y-b)^2 = r^2

      i found that out ... (x+5)^2 + (y-6)^2 = 5,

      BUT the next question says verify that the point P (-2,2) lies on the circle

      i dont know how to work it out help pl0x
      Sub x = -2 and y = 2 into the equation. It lies on the circle if the equation equals 5.
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      (Original post by im so academic)
      Sub x = -2 and y = 2 into the equation. It lies on the circle if the equation equals 5.
      I expanded the brackets and then subed it LHS is -16 and RHS is -20
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        (Original post by Skaterkid)
        I expanded the brackets and then subed it LHS is -16 and RHS is -20
        Is the original equation correct?
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        (Original post by Skaterkid)

        i found that out ... (x+5)^2 + (y-6)^2 = 5,


        5 !!!!!!
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          Yes, remember the equation of the circle equals r squared. There is a mistake when you tried to find out the equation of the circle.
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            (Original post by Skaterkid)
            I expanded the brackets and then subed it LHS is -16 and RHS is -20
            The RHS doesn't equal 20. You've substituted your values in wrong.
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              (Original post by ghostwalker)
              5 !!!!!!
              Yeah, I was a bit suspicious of that first. Usually the radius squared is square number.
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              (-2+5)^2=9
              (2-6)^2=16
              =25
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                (Original post by iPthreefifthteen)
                (-2+5)^2=9
                (2-6)^2=16
                =25
                :yep:
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                (Original post by iPthreefifthteen)
                (-2+5)^2=9
                (2-6)^2=16
                =25
                Is that the correct method to use in the exams?
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                (Original post by Skaterkid)
                Is that the correct method to use in the exams?
                It's as good as any
               
               
               
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