STRAND: Algebra TOPIC: Coordinates & graphs Measuring the rise and the run To measure the rise and the run for a straight line, follow these steps: 1. Select two points on the line. If the line goes through the origin, it is best to select the origin and any other point. If the line cuts both axes, select the x-intercept and the y-intercept. 2. Construct the gradient triangle, so that the two points are the vertices. 3. Measure the horizontal distance (that is, the distance along the horizontal side of a triangle) between the two points. This distance represents the run. Note that the run is always positive. 4. Measure the vertical distance (that is, the distance along the vertical side of a triangle) between the two points. This distance represents the rise. Note that if the line slopes upward from left to right, the rise is positive, while if the line slopes downward, the rise is negative. WORKED Example State the rise and the run for each of the following straight lines. y a b y 4 3 2 1 –4 –3 –2 –1 –1 –2 –3 –4 4 3 2 1 1 2 3 4 x –3 –2 –1–1 –2 –3 –4 1 2 3 4 5 6 THINK WRITE/DRAW a a 1 Since the line goes through the origin, select the origin and some other point. Draw the gradient triangle so that the selected points are the vertices. y 4 3 2 1 –4 –3 –2 –1 –1 –2 –3 –4 2 3 Measure the distance along the horizontal side of the triangle (that is, how much it is from 0 to 2). Hence state the value of the run. Measure the distance along the vertical side of the triangle (that is, how much it is from 0 to 3) to find the value of the rise. Since the line slopes upward from left to right, the rise is positive. x 3 2 1 2 3 4 Run = 2 Rise = 3 John Wiley & Sons Australia, Ltd 2001 STRAND: Algebra TOPIC: Coordinates & graphs SKILLBUILDER: Measuring the rise and the run THINK WRITE/DRAW b b Since the line cuts both axes, select the x- and y-intercepts. Draw the gradient triangle so that the selected points are the vertices. 1 y 4 3 2 1 –2 –3 –2 –1–1 –2 –3 –4 3 x Run = 6 Measure the distance along the horizontal side of the triangle (it is from 0 to 6) and hence state the value of the run. Measure the distance along the vertical side of the triangle (that is, from 0 to 2) to find the value of the rise. Since the line slopes downward from left to right, the rise is negative. 2 6 1 2 3 4 5 6 Rise = −2 Try these State the rise and the run for each of the following straight lines. 1 2 y 4 4 3 2 1 3 2 1 –3 –2 –1 –1 –2 –3 3 5 1 2 3 4 5 6 x 1 2 3 4 5 6 x 1 2 3 4 5 6 x 1 2 3 4 5 6 x y 4 3 2 1 1 2 3 4 5 6 x –3 –2 –1–1 –2 –3 6 y 4 3 2 1 –3 –2 –1 –1 –2 –3 –3 –2 –1–1 –2 –3 4 y 5 4 3 2 1 –3 –2 –1 –1 –2 –3 y y 4 3 2 1 1 2 3 4 5 6 x –3 –2 –1–1 –2 –3 John Wiley & Sons Australia, Ltd 2001 STRAND: Algebra TOPIC: Coordinates & graphs 7 SKILLBUILDER: Measuring the rise and the run 8 y 4 3 2 1 4 3 2 1 –3 –2 –1 –1 –2 –3 9 1 2 3 4 5 6 x –3 –2 –1 –1 –2 –3 10 y 1 2 3 4 5 6 x y 3 2 1 4 3 2 1 –3 –2 –1–1 –2 –3 y 1 2 3 x –4 –3 –2 –1–1 –2 –3 –4 1 2 x John Wiley & Sons Australia, Ltd 2001