Module 5 · Mensuration
Chapter 48: 2D Mensuration
Mensuration
3 topics
What this chapter covers
The 3 topics below make up 2D Mensuration on the CAT. Click any topic to open its notes, examples and practice test.
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Formula Reference Sheet
This chapter
Triangle & quadrilateral areas
| Triangle (base–height) | Area = ½ × b × h |
|---|---|
| Triangle (Heron, s = (a+b+c)/2) | Area = √[s(s−a)(s−b)(s−c)] |
| Triangle (two sides + angle) | Area = ½ × a × b × sinC |
| Equilateral triangle (side a) | Area = (√3 / 4) × a² ; height = (√3/2)a |
| Parallelogram / Rhombus | b × h ; rhombus = ½ × d₁ × d₂ |
| Trapezium (parallel sides a, b) | Area = ½ × (a + b) × h |
Circle, sector & segment
| Circle area & circumference | Area = πr² ; Circumference = 2πr |
|---|---|
| Sector area (angle θ°) | (θ/360) × πr² |
| Arc length (angle θ°) | (θ/360) × 2πr |
| Minor segment area | Sector − triangle = (θ/360)πr² − ½r²·sinθ |
| Ring (annulus) area | π(R² − r²) |
CAT reference
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