Key points
A The right-left direction on a graph or map. Parallel to the horizon. line is formed by coordinates with the same The number or quantity that does not vary. Eg, in the equation 𝒚 = 3𝒙 + 6, the 3 and 6 are constants, where 𝒙 and 𝒚 are variables.
\(y\)-coordinate (\(x\), \(y\)). This is generalised by the equation \(y = c\), where \(c\) is the constant \(y\)-coordinate.A The up-down direction on a graph or map. line is formed by coordinates with the same constant \(x\)-coordinate
(\(x\), \(y\)). This is generalised by the equation \(x = c\), where \(c\) is the constant \(x\)-coordinate.The \(x\)The line on a graph that runs horizontally (left-right) through the origin. It is used as a reference to measure from. is a horizontal line with equation \(y = 0\). The \(y\)The line on a graph that runs vertically (up-down) through the origin. It is used as a reference to measure from. is a vertical line with equation \(x = 0\)
A line is continuous and extends forever. It has an Unlimited, endless length. When drawing a shape, each side is a A specific part of a line between two points..
Plotting horizontal and vertical lines
A horizontal line is made up of The ordered pair of numbers (𝒙, 𝒚) that defines the position of a point. with a constant \(y\)-coordinate (\(c\)).The equation of the horizontal line is \(y = c\)
A vertical line is made up of coordinates with a constant \(x\)-coordinate (\(c\)).The equation of the vertical line is \(x = c\)
To draw the line \(y = c\):
- Find the The number or quantity that does not vary. Eg, in the equation 𝒚 = 3𝒙 + 6, the 3 and 6 are constants, where 𝒙 and 𝒚 are variables. value \(c\) on the \(y\)-axis.
- Draw a horizontal line through the coordinates (0, \(c\)).
- Label the line with its equation.
To draw the line \(x = c\):
- Find the constant value \(c\) on the \(x\)-axis.
- Draw a vertical line through the coordinates (\(c\), 0).
- Label the line with its equation.
Examples
Image caption, A horizontal line is made up of coordinates with a constant 𝒚-coordinate.
1 of 8
Question
Draw the line \(x = -4\)
- Find the constant value (-4) on the \(x\)-axis.
- Draw a vertical line through the coordinates (-4, 0).
- Label the line with its equation, \(x = -4\)
Finding equations of horizontal and vertical lines
The equation of the \(x\)-axis is \(y = 0\)
The equation of the \(y\)-axis is \(x = 0\)
To find the equation of a horizontal line, or line segment:
- Extend the line to find the constant (\(c\)) at which it meets the \(y\)-axis.
- Label the line with the equation \(y = c\)
For a line segment, state the values of \(x\) for which the line segment is drawn.
To find the equation of a vertical line, or line segment:
- Extend the line to find the constant (\(c\)) at which it meets the \(x\)-axis.
- Label the line with the equation \(x = c\)
For a line segment, state the values of \(y\) for which the line segment is drawn.
Example
Image caption, Find the equations of each line segment that forms the rectangle.
1 of 4
Question
Give the equations of the three lines.
- Line A is vertical and crosses the \(x\)-axis at 2. The equation of line A is \(x = 2\)
- Line B is horizontal and crosses the \(y\)-axis at 0. The equation of line B is \(y = 0\), which is the equation of the \(x\)-axis.
- Line C is horizontal and crosses the \(y\)-axis at -3. The equation of line C is \(y = -3\)
Practise horizontal and vertical lines
Quiz
Practise plotting horizontal and vertical lines with this quiz. You may need a pen and paper to help you with your answers.
Play Sudoku with BBC Bitesize!
Every weekday we release brand new easy, medium and hard Sudoku puzzles. Perfect for testing your skill with numbers and logic.
More on Graphs
Find out more by working through a topic
- count4 of 7
- count6 of 7
- count7 of 7
