Back to Edexcel Angles, Lines & Polygons (F) Home
4.1 G) Angle Rules – Parallel Lines: Part 1
4.1 G) Angle Rules – Parallel Lines: Part 1
Parallel lines are lines that are always the same distance apart, which means that the lines will never meet one another. We use a “>” sign to show lines that are parallel to one another. If there are more than one set of parallel lines, we use “>>” to indicate the next set of parallel line.
A straight line that intersects a set of parallel lines is known as an intersecting transversal (you don’t need to remember this name).
There are a few different angle rules to do with a set of parallel lines with an intersecting transversal line and we are going to look at some of them in this section.
Corresponding Angles
The corresponding angle rule is sometimes referred to as the F rule and this is because an F shape is created on the diagram. Corresponding angles are equal to one another.
The corresponding angle rule is sometimes referred to as the F rule and this is because an F shape is created on the diagram. Corresponding angles are equal to one another.
On the diagram above, I have highlighted the F on the lines. The two angles that are black are the same as one another.
This is not the only pair of corresponding angles on the above diagram; there are 4 corresponding angles in total. All of these corresponding angles and the F’s are shown below (the top left one is the same as the one above):
This is not the only pair of corresponding angles on the above diagram; there are 4 corresponding angles in total. All of these corresponding angles and the F’s are shown below (the top left one is the same as the one above):
Alternate Angles
Alternate angles are also known as Z angle and this is because a Z shape is created on the diagram. Alternate angles are equal to one another.
Alternate angles are also known as Z angle and this is because a Z shape is created on the diagram. Alternate angles are equal to one another.
I have highlighted the Z shape on the above diagram and the two black angles are equal to one another.
There is another set of alternate angles on the diagram above and this set is shown below.
There is another set of alternate angles on the diagram above and this set is shown below.
Interior Angles
Angles that are on one side of the intersecting transversal and between the parallel lines add up to 180°. This rule creates a C shape.
Angles that are on one side of the intersecting transversal and between the parallel lines add up to 180°. This rule creates a C shape.
Angles a and b will add up to 180°.
There is another pair of angles that will add up to 180° and these are shown below.
Angles c and d will add up to 180°.
Vertically Opposite Angles
We are also able to see vertically opposite angles in the lines above. The vertically opposite rule states that vertically opposite angles are equal to one another. We went through the vertically opposite angle rule in the previous section (click here to be taken through to that section). There are 4 pairs of vertically opposite angles on the diagram that we have been looking at. All of these 4 pairs are shown below:
We are also able to see vertically opposite angles in the lines above. The vertically opposite rule states that vertically opposite angles are equal to one another. We went through the vertically opposite angle rule in the previous section (click here to be taken through to that section). There are 4 pairs of vertically opposite angles on the diagram that we have been looking at. All of these 4 pairs are shown below: