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How to Graph in Geometry

In any geometry class, you will be asked to graph equations, lines or points. Graphing may seem like a daunting task at first, but it is actually a very simple process, as long as you are given information, such as coordinates and a formula containing the variables, x and y.

Instructions

  1. Graphing Lines

    • 1

      Draw an x-y axis on a sheet of graph paper. The x-axis is a straight horizontal line. The y-axis is a straight vertical line that intersects the x-axis, preferably in the center. The point of intersection is the origin (0,0).

    • 2

      Write the equation in y=mx+b form, where m is the slope and b is the y-intercept or the point at which the line hits the y-axis. For example, rewrite the equation: 5=2x+2y.

      2y= 4-2x

      2y= -2x+4

      y= -x +2

    • 3

      Draw a point at the y-intercept, i.e., 2. From the origin, count two units up from the y-axis and mark this point.

    • 4

      Draw the slope, i.e., -1. From the y-intercept, go down one unit on the y-axis and move one unit horizontally to the right (x-plane). Mark this point. Repeat moving down one unit and moving to the right one unit and marking the point. This is the linear slope. Draw a line connecting the dots, using a ruler.

    Graphing Coordinates

    • 5

      Draw an x-y axis on a sheet of graph paper. The x-axis is a straight horizontal line. The y-axis is a straight vertical line that intersects the x-axis, preferably in the center. The point of intersection is the origin (0,0).

    • 6

      Read the equation: Graph the coordinates (4,2) and (-2,1) and find the slope of the line. In any coordinate, (x,y), the first value is the x-coordinate and the second value is the y-coordinate.

    • 7

      Graph the first coordinate (4,2). From the origin, count four (x-coordinate) units to the right on the x-axis and two (y-coordinate) units above. Mark this point. Graph the second coordinate (-2,1). From the origin, count two units to the left on the x-axis and one unit above. Mark this point. Draw a straight line through these points using a ruler. Each point on this line is a coordinate of the line.

    • 8

      Find the slope. Given the two coordinates, use the formula (y2-y1)/(x2-x1): (1-2)/(-2-4)= -1/-6=1/6. The slope of the line is 1/6. Recall the y=mx +b equation for a line. Substitute one of the coordinates (4,2) and the slope (1/6) into the equation and solve for b: 2=1/6(4) +b.

      2=2/3 +b

      b= 4/3

    • 9

      Rewrite the equation of the line using the y-intercept (4/3): y=1/6x +4/3.

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