Geometry & MeasuresKey Facts

Circle Vocabulary

Part of Properties of CirclesGCSE Mathematics

This key facts covers Circle Vocabulary within Properties of Circles for GCSE Mathematics. Revise Properties of Circles in Geometry & Measures for GCSE Mathematics with 10 exam-style questions and 4 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 2 of 5 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 2 of 5

Practice

10 questions

Recall

4 flashcards

Circle Vocabulary

Radius (r)Distance from centre to edge
Diameter (d)Distance across through centre (d = 2r)
CircumferenceDistance around the outside (C = πd)
ChordLine segment with both ends on the circle
TangentLine that touches circle at ONE point (90° to radius)
ArcPart of the circumference
Sector"Pizza slice" - area between two radii and an arc
SegmentRegion between a chord and an arc

Keep building this topic

Read this section alongside the surrounding pages in Properties of Circles. That gives you the full topic sequence instead of a single isolated revision point.

Practice Questions for Properties of Circles

A triangle is drawn inside a circle with one side being the diameter. What is the size of the angle at the circumference opposite the diameter?

  • A. 45°
  • B. 60°
  • C. 90°
  • D. 180°
1 markfoundation

Prove that the angle in a semicircle is 90°, using the theorem that the angle at the centre is twice the angle at the circumference.

3 markshigher

Quick Recall Flashcards

Tangent Rule
A tangent ALWAYS meets the radius at 90° at the point of contact.
Tangent
Line touching circle at one point, perpendicular to radius

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