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Year 8

Co-interior angles

I can recognise that a pair of parallel lines traversed by a straight line produces supplementary co-interior angles.

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New
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Year 8

Co-interior angles

I can recognise that a pair of parallel lines traversed by a straight line produces supplementary co-interior angles.

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Lesson details

Key learning points

  1. Co-interior angles can be identified in an arrangement of 3 line segments.
  2. If two of the lines are parallel then these angles are supplementary.
  3. Knowledge of co-interior angles can be used to find unknown angles.
  4. Knowledge of co-interior, corresponding and alternate angles can be used to find unknown angles.

Keywords

  • Co-interior - Co-interior angles are on the same side of the transversal line and in between the two other lines.

Common misconception

Pupils may believe that the co-interior angles are equal, like alternate and corresponding angles.

Have pupils draw a pair of parallel lines and a transversal line themselves, identify the co-interior angles, are they equal?


To help you plan your year 8 maths lesson on: Co-interior angles, download all teaching resources for free and adapt to suit your pupils' needs...

It can be helpful to show the pupils multiple diagrams with co-interior, alternate and corresponding angles identified and have the pupils decide which of the three is being shown at that point.
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Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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6 Questions

Q1.
The value of the angle marked $$a$$ is °.
An image in a quiz
Correct Answer: 128, one hundred and twenty eight
Q2.
The value of the angle marked $$x$$ is °.
An image in a quiz
Correct Answer: 53, fifty three
Q3.
Work out the value of $$m$$.
An image in a quiz
12
Correct answer: 61
85
168
Q4.
Which pair of line segments are equal in length in this diagram?
An image in a quiz
Correct answer: AE
BF
CG
Correct answer: IJ
FG
Q5.
Alternate angles are a pair of angles both between or both outside two line segments that are on opposite sides of the that cuts them.
Correct Answer: transversal
Q6.
Which of the following show a pair of equal corresponding angles?
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz

6 Questions

Q1.
Co-interior angles are on the side of the transversal line and in between the two other lines.
Correct Answer: same
Q2.
Which of these diagrams show co-interior angles?
An image in a quiz
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q3.
Which pairs of angles are co-interior?
An image in a quiz
$$a$$° and $$h$$°
Correct answer: $$c$$° and $$f$$°
$$b$$° and $$h$$°
Correct answer: $$d$$° and $$e$$°
$$c$$° and $$e$$°
Q4.
If the co-interior angles are in parallel lines then the angles are .
equal
Correct answer: supplementary
conjugate
Q5.
The angle marked $$n$$° is ° as $$n$$° and 118° are supplementary co-interior angles.
An image in a quiz
Correct Answer: 62, sixty two, 62°
Q6.
Use this diagram to match pairs of supplementary co-interior angles.
An image in a quiz
Correct Answer:c,f
tick

f

Correct Answer:d,e
tick

e

Correct Answer:o,j
tick

j

Correct Answer:p,i
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i

Correct Answer:h,k
tick

k

Correct Answer:a,n
tick

n