Skip to main content

Linear relationships - advanced

This lesson comprises four (4) master classes focusing on:

  • Gradient/slope
  • Line equations in the gradient-intercept form
  • Line equations in the point-gradient form
  • Parallel and perpendicular lines
  • Midpoint of line segments
  • Distance between points
  • Translations and reflections in an axis

Content:

MA5-LIN-C-01


Find the midpoint and gradient of a line segment (interval) on the Cartesian plane

  • Plot and join 2 points to form an interval on the Cartesian plane and use the interval as the hypotenuse of a right-angled triangle
  • Apply the relationship gradient \( m=\frac{rise}{run} \) to find the gradient/slope of the interval joining the 2 points
  • Distinguish between intervals with positive and negative gradients from a diagram
  • Explain why horizontal intervals have a gradient of 0 and vertical intervals have undefined gradients using the gradient relationship
  • Determine the midpoint of horizontal and vertical intervals on the Cartesian plane
  • Apply the process for calculating the mean to find the midpoint, of the interval joining 2 points on the Cartesian plane
  • Use graphing applications to find the midpoint and gradient/slope of an interval

Find the distance between 2 points located on the Cartesian plane

  • Use the interval between 2 points as the hypotenuse of a right-angled triangle on the Cartesian plane and apply Pythagoras’ theorem to determine the length of the interval joining the 2 points
  • Use graphing applications to find the distance between 2 points on the Cartesian plane

Recognise and graph equations

  • Recognise that equations of the form \( y=mx+c \) represent linear relationships or straight lines
  • Construct tables of values and use coordinates to graph a variety of linear relationships on the Cartesian plane, with and without digital tools
  • Identify the x- and y-intercepts of lines
  • Determine whether a point lies on a line using substitution

Examine parallel, horizontal and vertical lines

  • Explain that parallel lines have equal gradients/slopes
  • Explain why the x-axis has the equation \( y=0 \) and the y-axis has the equation \( x=0 \)
  • Recognise \( y=c \) as a line parallel to the x-axis and \( x=k \) as a line parallel to the y-axis
  • Graph vertical and horizontal lines

 

MA5-LIN-C-02


Examine the gradient/slope-intercept form

  • Interpret the coefficient of \( x(m) \) as the gradient/slope, and the constant \( c \) as the y-intercept for equations of the form \( y=mx+c \)
  • Find the equation of a straight line in the form \( y=mx+c \), given the gradient/slope and the y-intercept of the line
  • Graph equations of the form \( y=mx+c \) by using the gradient and the y-intercept
  • Determine the gradient and y-intercept of a straight line from its graph and apply these values to determine the equation of the line
  • Explain the effect of increasing or decreasing the gradient with or without digital tools
  • Recognise and describe linear relationships in real-life contexts

Find the equations of parallel and perpendicular lines

  • Explain that 2 straight lines are perpendicular if the product of their gradients is −1
  • Find the equation of a straight line that is parallel or perpendicular to another given line by applying \( y=mx+c \)

 

MA5-LIN-P-01


Apply formulas to find the midpoint and gradient/slope of an interval on the Cartesian plane

  • Apply the formula to find the midpoint of the interval joining 2 points on the Cartesian plane: \( M(x,y)=(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2}) \)
  • Use the relationship \( m=\frac{rise}{run} \) to establish the formula for the gradient/slope \( m \) of the interval joining the 2 points \( (x_1, y_1) \) and \( (x_1, y_2) \) on the Cartesian plane: \( m=\frac{y_2-y_1}{x_2-x_1} \)
  • Apply the gradient formula to find the gradient of the interval joining 2 points on the Cartesian plane

Apply the distance formula to find the distance between 2 points located on the Cartesian plane

  • Apply knowledge of Pythagoras’ theorem to establish the formula for the distance \( (d) \) between the 2 points \( (x_1, y_1) \) and \( (x_1, y_2) \) on the Cartesian plane: \( d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\)
  • Apply the distance formula to find the distance between 2 points on the Cartesian plane

Use various forms of the equation of a straight line

  • Rearrange linear equations from gradient–intercept form \( (y=mx+c) \) to general form \( (ax+by+c=0) \) and vice versa
  • Find the x- and y-intercepts of a straight line in any form
  • Graph the equation of a straight line in any form
  • Use the point–gradient form \( (y-y_1=m(x-x_1)) \) or the gradient–intercept form \( (y=mx+c) \) to find the equation of a line passing through a point \( (x_1, y_1) \), with a given gradient
  • Use the gradient and the point–gradient form to find the equation of a line passing through 2 points
  • Find the equation of a line that is parallel or perpendicular to a given line in any form
  • Determine and justify whether 2 given lines are parallel or perpendicular

Solve problems by applying coordinate geometry formulas

  • Solve problems including those involving geometrical figures by applying coordinate geometry formulas

Identify line and rotational symmetries

  • Identify lines (axes) and rotational symmetry in plane shapes
  • Identify line and rotational symmetry in various linear and non-linear graphs

Describe translations, reflections in an axis, and rotations through multiples of 90 degrees on the Cartesian plane, using coordinates

  • Apply the notation \( P' \) to name the image resulting from applying a transformation to a point \( P \) on the Cartesian plane
  • Determine and plot the coordinates for \( P' \) resulting from translating \( P \) one or more times
  • Determine and plot the coordinates for \( P' \) resulting from reflecting \( P \) in either the x- or y-axis
  • Determine and plot the coordinates for \( P' \) resulting from rotating \( P \) by a multiple of \( 90^\circ \) about the origin