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Math Help - Linear equation - Graphing - Cant find 2nd point

  1. #1
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    Linear equation - Graphing - Cant find 2nd point

    Hey,

    My problem is i have one point (2.15,1.1) in meters.
    ive been told i want to find the other point/coordinate but i am unsure how to do so.
    I know the gradient of my linear line is -3.7/1.8 and the distance away from point 1 is going to be 1.2metres.

    I am unsure what to do, i have found the equation of this line which is Y=(-3.7/1.8)x + 5.52.

    Thanks in advance to anybody who knows what i should do
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  2. #2
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    Quote Originally Posted by Dandonny View Post
    Hey,

    My problem is i have one point (2.15,1.1) in meters.
    ive been told i want to find the other point/coordinate but i am unsure how to do so.
    I know the gradient of my linear line is -3.7/1.8 and the distance away from point 1 is going to be 1.2metres.

    I am unsure what to do, i have found the equation of this line which is Y=(-3.7/1.8)x + 5.52.

    Thanks in advance to anybody who knows what i should do
    1. To be exact (as much as possible) your equation of the line is:

    y = -\dfrac{37}{18} x +\dfrac{1987}{360}

    2. The point you are looking for has the coordinates P(p,y_P) with y_P= -\dfrac{37}{18} p +\dfrac{1987}{360}

    3. Now use the distance formula which yields the distance between 2 points:

    d = \sqrt{(x_1-x_2)^2+(y_1-y_2)^2}

    With your example you'll get:

    1.2=\sqrt{(p-2.1)^2+\left(-\dfrac{37}{18} p +\dfrac{1987}{360}-1.1\right)^2}

    4. Solve for p and consequently calculate y_P. You should get two different points!
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