Tham khảo tài liệu 'structure question 2', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | ------------------------------------ THEA MATH REVIEW ------------------------------------------- -3 1 5 -4 . M 2 M 2 2 M -1 2 Note There is no such thing as the midpoint of a line as lines are infinite in length. Slope The slope of a line or line segment is a numerical value given to show how steep a line is. A line or segment can have one of four types of slope A line with a positive slope increases from the bottom left to the upper right on a graph. A line with a negative slope decreases from the upper left to the bottom right on a graph. A horizontal line is said to have a zero slope. A vertical line is said to have no slope undefined . Parallel lines have equal slopes. Perpendicular lines have slopes that are negative reciprocals of each other. Negative slope 5 4 3. 2- 1- I -1 1 2 4 5 -2 . 3. -4. 5 Zero slope y 5 4 3 2 1 1 -2 -1 . 1 2 4 5 2 . 3. 4- -5- Undefined no slope 145 THEA MATH REVIEW The slope of a line can be found if you know the coordinates of any two points that lie on the line. It does not matter which two points you use. It is found by writing the change in the y-coordinates of any two points on the line over the change in the corresponding x-coordinates. This is also known as the rise over the run. The formula for the slope of a line or line segment containing points x1 y1 and x2 y2 m - . Example Determine the slope of the line joining points A -3 5 and B 1 -4 . m Let x1 y1 represent point A and let x2 y2 represent point B. This means that x1 -3 y1 5 x2 1 and y2 -4. Substituting these values into the formula gives us y2 1 x2- Xi m -4-5 1 - -3 m AL 4 Example Determine the slope of the line graphed below. Two points that can be easily determined on the graph are 3 1 and 0 -1 . Let 3 1 x1 y1 and let 0 -1 x2 y2 . This means that x1 3 y1 1 x2 0 and y2 -1. Substituting these values into the formula gives us 146 THEA MATH REVIEW -1-1 m m Í3 2 Note If you know the slope and at least one point on a line you can find the coordinate point of other points .
