Parts of a circle

This revision sheet is a handy printable for GCSE students which provides a clear overview of the key components of a circle, including the radius, diameter, circumference, and area. Clear, concise definitions are provided for each term, along with illustrative diagrams to aid understanding.

What’s included

• Free printable revision sheet with clear definitions and diagrams of the parts of a circle
• An editable version of the revision sheet, to adapt to suit students’ needs (subscribers only)

Who is this useful for?

This revision sheet is an excellent tool for GCSE students who are preparing for their maths exams. It provides a clear, focused review of an important topic and offers a range of exercises to help students apply their knowledge.

What are the parts of a circle?

GCSE maths students need to understand the key components of a circle, including the radius which is the line from the centre to the circumference, the diameter which is twice the radius, the circumference which is the outer boundary of the circle, and the area which is the space enclosed by the circle. They should be able to identify these on a diagram and calculate the circumference and area given the radius or diameter.

Common misconceptions 

• Confusing the radius and diameter: Many students mistakenly believe that the radius and diameter are the same, forgetting that the diameter is twice the length of the radius.
• Misunderstanding Pi: Some students struggle with the concept of Pi, often not understanding that it represents the ratio of the circumference of a circle to its diameter.
• Calculating the area incorrectly: A common error is to use the diameter instead of the radius when calculating the area of a circle.
• Misidentifying the circumference: Students often confuse the circumference with the area, not realizing that the circumference is the perimeter of the circle, not the space it encloses.

Looking for more like this?

If you’re looking for more helpful resources to revise or learn about the parts of a circle or circle theorems, why not try:

• Circle posters (includes circle definitions, circle formulae and circle theorems)
• Tangent to a circle lesson
• Tangent to a circle practice worksheets
• Plenary — circles (area and circumference)
• Circle theorems workout

Browse all circle resources.