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Math Help - perpendicular lines

  1. #1
    Junior Member Bartimaeus's Avatar
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    perpendicular lines

    The question is:

    What is the equation of a line perpendicular to the x-axis and passes through (3,-2)?

    By graphing the line, we know that it is x=3, but how do you find that out without graphing.
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  2. #2
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    What is the equation of a line perpendicular to the x-axis and passes through (a,b)? Well x=a


    What is the equation of a line perpendicular to the y-axis and passes through (a,b)? Well y=b
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  3. #3
    Junior Member Dergyll's Avatar
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    You know that a line perpendicular to the x-axis must be vertical and must have an equation of x=something. In the case of (3,-2), it doesn't matter what the Y value is as long as you have the x value and know where on the x-axis the point is, in this case, 3. So the equation will be x=3. If the line were to be horizontal, you would know that the x value must be 0 since it does not intercept the x-axis (there is an exception when the line is on the x-axis though) and the concept would be backwards where it will be y=something.

    Sometimes I find it hopeful to draw mental pictures of the situation.

    Hope this helps
    Derg
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  4. #4
    Junior Member Bartimaeus's Avatar
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    Smile

    thanx
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