Quadrilaterals & Polygons for CAT: Formulas, Weightage & Question Types
Regular hexagons and octagons, rhombus diagonals, trapeziums and polygon angles.
Quadrilaterals & Polygons formula sheet
Everything CAT needs from Quadrilaterals & Polygons, 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 a side, a height, and the diagonals.
Rectangle and square
| Rectangle, area | |
| Rectangle, perimeter | |
| Rectangle, diagonal | — the square root is not optional |
| Square, area | |
| Square, diagonal | |
| Rectangle in a circle | the diagonal is the diameter, so |
Parallelogram
| Area | |
| Height versus side | the slant side, always — this is a hidden inequality |
| Diagonals | they bisect each other |
| Diagonal identity |
Rhombus — four equal sides
| Diagonals | perpendicular bisectors of each other |
| Area | |
| Side and diagonals | |
| Area, from the angle | |
| Inradius |
Trapezium
| Area | |
| A leg perpendicular to both parallels | that leg is the height |
| Legs extended to a point | the two triangles are similar, in the ratio of the parallel sides |
Circles in and around
| A circle fits inside a quadrilateral exactly when | |
| Then | |
| A circle fits around it exactly when | opposite angles add to |
Any regular polygon, sides
| Exterior angle | |
| Interior angle | |
| The quick one | interior exterior |
| Sum of interior angles | |
| Number of diagonals |
Regular hexagon, side — six equilateral triangles
| Area | |
| Short diagonal, spanning two sides | |
| Long diagonal, straight across | |
| Distance from centre to a vertex |
Regular octagon, side
| Area | |
| Diagonal spanning two sides |
Limits
| Each side of a quadrilateral | is less than the sum of the other three |
| Fixed perimeter | the square has the largest area |
| Fixed area | the square has the smallest perimeter |
The 7 Quadrilaterals & Polygons question types CAT repeats
Past CAT papers return to the same few shapes. Learn to recognise them and most questions become a known routine. Beyond these, CAT has asked 1 rarer one-off shape here.
- 01
Inside a regular hexagon or octagon
- 02
A rectangle under a constraint
- 03
A trapezium
- 04
A rhombus, which means its diagonals
- 05
Areas split inside a rectangle or square
- 06
Regular polygon angle arithmetic
- 07
A parallelogram
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Quadrilaterals & Polygons in CAT: quick answers
- How many Quadrilaterals & Polygons questions come in CAT Quant?
- About 1.3 questions in a 22-question Quant section, worth roughly 4 marks. Quadrilaterals & Polygons appeared in 21 of the 24 CAT papers from 2017 to 2025, 32 questions in all, which ranks it 6 of 25 Quant chapters.
- Are Quadrilaterals & Polygons questions in CAT MCQ or TITA?
- 25% of the Quadrilaterals & Polygons questions asked since 2017 were TITA (type in the answer, no negative marking). The rest were multiple choice.
- What types of Quadrilaterals & Polygons questions does CAT ask?
- CAT keeps returning to 7 question shapes in Quadrilaterals & Polygons: Inside a regular hexagon or octagon; A rectangle under a constraint; A trapezium; A rhombus, which means its diagonals; Areas split inside a rectangle or square; Regular polygon angle arithmetic; A parallelogram.