Angles & parallel lines · Ages 12–13
Corresponding, alternate and interior angles
Corresponding F, alternate Z, interior C.
How to do it
Method
Corresponding F, alternate Z, interior C
∠AEF and ∠EFD: opposite sides, both between the lines, so alternate
Another way
Ask two questions
Same side? Between the lines?
In full
A line (the transversal) cuts two lines and makes four angles at each crossing. Corresponding angles are on the same side of the transversal and both above their lines (or both below): an F shape. Alternate angles are on opposite sides of the transversal and both between the two lines: a Z shape. Interior angles on the same side are on the same side and both between the lines: a C shape. Another way to tell: by place. Ask "same side of the transversal?", then "between the two lines?". The names depend only on place; they hold whether or not the lines are parallel.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
The two lines in the picture are parallel. Which angle corresponds to a?
- A. d
- B. c
- C. b
- D. e
Choose the right answer
Show the answer and working
Answer: B. c
a's corresponding angle is at the other crossing, on the same side of the transversal, and above its line just as a is (or below, as a is): together an F.
Example 2
In the picture, a and b are corresponding angles.
True or false?
Show the answer and working
Answer: True
Corresponding angles are on one side of the transversal, one between the lines and one outside (an F). The name depends only on place: parallel or not, it is the same.
Example 3
The two lines in the picture are parallel. Which pair are interior angles on the same side?
- A. a and b
- B. a and c
- C. a and d
- D. b and c
Choose the right answer
Show the answer and working
Answer: A. a and b
Interior angles on the same side are on one side of the transversal and both between the lines (a C). Check each pair for both; only one pair passes.
Practice questions to try
Try these 5; the answers are at the end. For a whole worksheet, see VIP worksheets below.
1.In the picture, a and b are interior angles on the same side.
True or false?
Answer:
2.The two lines in the picture are parallel. What are a and b?
- A. alternate angles
- B. vertically opposite angles
- C. corresponding angles
- D. interior angles on the same side
Choose the right answer
Answer:
3.In the picture, a and b are corresponding angles.
True or false?
Answer:
4.In each picture two lines, not necessarily parallel, are cut by a transversal, one angle 130°. In which are a and b corresponding angles?
- A
- B
- C
- D
Choose the right picture
Answer:
5.The two lines in the picture are parallel. Which pair are interior angles on the same side?
- A. b and c
- B. a and d
- C. a and c
- D. a and b
Choose the right answer
Answer:
All the answers
- 1. True
- 2. D. interior angles on the same side
- 3. True
- 4. C
- 5. C. a and c
VIP practice notes and papers
Aimed at tests and exams: questions on this topic, new every time, to print or save as a PDF.
- Practice notes: The key point, worked examples step by step, then questions of the same kind to follow, hints fading
- Practice paper: Set out in parts like a school paper, marked, with answers and full working
Start playingPlay and learn in the secondary world, Star Galaxy: animated methods, monster battles, a review of every mistake