Topic Coordinate Geometry Estimated reading: 4 minutes 102 views Coordinates of a PointRead the coordinates of a pointCoordinates of a points – are the values of ? and ? enclosed by the bracket which are used to describe the position of a point in the planeThe plane used is called ?? − plane and it has two axis; horizontal axis known as ? − axis and; vertical axis known as ? − axisA Point Given its CoordinatesPlot a point given its coordinatesSuppose you were told to locate (5, 2) on the plane. Where would you look? To understand the meaning of (5, 2), you have to know the following rule: The x-coordinate (always comes first. The first number (the first coordinate) is always on the horizontal axis.A Point on the CoordinatesLocate a point on the coordinatesThe location of (2,5) is shown on the coordinate grid below. Thex-coordinate is 2. They-coordinate is 5. To locate (2,5), move 2 units to the right on thex-axis and 5 units up on they-axis.The order in which you write x– and y-coordinates in an ordered pair is very important. Th ex-coordinate always comes first, followed by they-coordinate. As you can see in the coordinate grid below, the ordered pairs (3,4) and (4,3) refer to two different points!Gradient (Slope) of a LineThe Gradient of a Line Given Two PointsCalculate the gradient of a line given two pointsGradient or slope of a line – is defined as the measure of steepness of the line. When using coordinates, gradient is defined as change in ? to the change in ?.Consider two points ? (?1, ?1)and (? ?2, ?2), the slope between the two points is given by:Example 1Find the gradient of the lines joining:(5, 1) and (2,−2)(4,−2) and (−1, 0)(−2,−3) and (−4,−7)SolutionExample 2The line joining (2,−3) and (?, 5) has gradient −2. Find ?Find the value of ? if the line joining the points (−5,−3) and (6,?) has a slope of½SolutionEquation of a LineThe Equations of a Line Given the Coordinates of Two Points on a LineFind the equations of a line given the coordinates of two points on a lineThe equation of a straight line can be determined if one of the following is given:-The gradient and the ? − intercept (at x = 0) or ? − intercept ( at y=0)The gradient and a point on the lineSince only one point is given, thenTwo points on the lineExample 3Find the equation of the line with the followingGradient 2 and ? − intercept −4Gradient −2⁄3and passing through the point (2, 4)Passing through the points (3, 4) and (4, 5)SolutionDivide by the negative sign, (−), throughout the equation∴The equation of the line is 2? + 3? − 16 = 0The equation of a line can be expressed in two forms?? + ?? + ? = 0 and? = ?? + ?Consider the equation of the form ? = ?? + ?? = Gradient of the lineExample 4Find the gradient of the following lines2? = 5? + 12? + 3? = 5? + ? = 3SolutionInterceptsThe line of the form ? = ?? + ?, crosses the ? − ???? when ? = 0 and also crosses ? − ???? when ? = 0See the figure belowThereforeto get ? − intercept, let ? = 0 andto get ? − intercept, let ? = 0From the line, ? = ?? + ?? − intercept, let ? = 0? = ? 0 + ? = 0 + ? = ?? − intercept = cTherefore, in the equation of the form ? = ?? + ?, ? is the gradient and ? is the ? − interceptExample 5Find the ? − intercepts of the following linesSolutionGraphs of Linear EquationsThe Table of ValueForm the table of valueThe graph of a straight line can be drawn by using two methods:By using interceptsBy using the table of valuesExample 6Sketch the graph of ? = 2? − 1SolutionThe Graph of a Linear EquationDraw the graph of a linear equationBy using the table of valuesSimultaneous EquationsLinear Simultaneous Equations GraphicallySolve linear simultaneous equations graphicallyUse the intercepts to plot the straight lines of the simultaneous equations. The point where the two lines cross each other is the solution to the simultaneous equationsExample 7Solve the following simultaneous equations by graphical methodSolutionConsider: ? + ? = 4If ? = 0, 0 + ? = 4 ? = 4If ? = 0, ? + 0 = 4 ? = 4Draw a straight line through the points 0, 4 and 4, 0 on the ?? − planeConsider: 2? − ? = 2If ? = 0, 0 − ? = 2 ? = −2If ? = 0, 2? − 0 = 2 ? = 1Draw a straight line through the points (0,−2) and (1, 0) on the ?? − planeFrom the graph above the two lines meet at the point 2, 2 , therefore ? = 2 ??? ? = 2Tagged:Form 1GeometryMathematicsNotes Topic - Previous Ratio, Profit And Loss Next - Topic Perimeters And Areas