The Slope of A Line |
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The Angle From the Horizontal - Rise Over Run | |||||||
When the slope of the line is 0, you know that the line is horizontal and you know it's a vertical line when the slope of a line is undefined. In the Figure
below, the subscripts on point A, B and C indicate the fact that there
are three points on the line. The
change in y whether up or down is divided by the change in x
going to the right, this is the 'rise over run' concept. When the slope passes through a point A(x_{1}, y_{1}) then y_{1} = mx_{1} + b or with subtraction y - y_{1} = m (x - x_{1}) You now have the slope-point form of the equation of a line. You can also express the slope of a line with the coordinates of points on the line. For instance, in the above figure, A(x, y) and B(s, y) are on the line y= mx + b : m = tan q = therefore, you can use the following for the equation of the line AB:
The equations of lines with slope 2 through the points would be: For (-2,1) the equation would be: 2x - y + 5 = 0. For (-1, -1) the equation would be: 2x - y + 1 = 0 That is it!!! Try Algebra for more interesting concepts. |