Circles for CAT: Formulas, Weightage & Question Types
Curved areas, chords, angles in a circle, tangents and touching circles.
Circles formula sheet
Everything CAT needs from Circles, in one place. Bookmark it for revision; the lesson in the app explains where each line comes from and when to reach for it.
Everything for this chapter, in one place. is the radius, an angle at the centre in degrees.
Basics
| Circumference | |
| Area | |
| Arc length | |
| Sector area | |
| Segment area | sector triangle |
| Triangle inside a sector |
Chords
| The perpendicular from the centre | bisects the chord |
| So, with the distance from the centre | |
| Chord from the central angle | |
| Equal chords | are equidistant from the centre |
| Intersecting chords at |
Angles
| Angle at the centre | twice the angle at the circumference on the same arc |
| Angle in a semicircle | |
| Angles in the same segment | are equal |
| Cyclic quadrilateral | opposite angles add to |
Tangents
| A tangent | is perpendicular to the radius at the point of contact |
| Two tangents from one point | are equal in length |
| Length of a tangent from distance | |
| Two tangents meeting at angle | the point is at from the centre |
| With an inner tangent line |
Touching circles
| Touching externally | centres are apart |
| Touching internally | centres are apart |
| Three circles on a common tangent line | |
| Three equal circles of radius , mutually touching | the enclosing circle has , the inner one |
The 5 Circles question types CAT repeats
Past CAT papers return to the same few shapes. Learn to recognise them and most questions become a known routine.
- 01
The area of a curved region
- 02
A chord, and its distance from the centre
- 03
Angles in a circle
- 04
Circles that touch each other
- 05
Tangents, or intersecting chords
Is Circles costing you marks?
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Circles in CAT: quick answers
- How many Circles questions come in CAT Quant?
- About 0.4 questions in a 22-question Quant section, worth roughly 1 marks. Circles appeared in 13 of the 24 CAT papers from 2017 to 2025, 16 questions in all, which ranks it 21 of 25 Quant chapters.
- Are Circles questions in CAT MCQ or TITA?
- 19% of the Circles questions asked since 2017 were TITA (type in the answer, no negative marking). The rest were multiple choice.
- What types of Circles questions does CAT ask?
- CAT keeps returning to 5 question shapes in Circles: The area of a curved region; A chord, and its distance from the centre; Angles in a circle; Circles that touch each other; Tangents, or intersecting chords.