Mensuration (क्षेत्रमिति’) in 3D

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1 गोला (sphere)

 

  • Volume (आयतन): (V) = 4/3* πr3

  • Surface Area(पृष्ठीय क्षेत्रफल): A = 4πr²
  • Diameter (व्यास): d = 2r
  • Circumference(वक्र पृष्ठीय): C = 2πr

2 CYLINDER (बेलन)

 

Cylinder Formulas (बेलन के सूत्र)

  • r = Radius of the cylinder base (बेलन के आधार की त्रिज्या)
  • h = Height of the cylinder (बेलन की ऊँचाई)
  • π = Pi ( 3.14  ,(22\7)) 

1. Volume of a Cylinder (बेलन का आयतन)
The amount of 3-dimensional space enclosed by the cylinder.

:      V = πr²h

2. Curved Surface Area / Lateral Surface Area (वक्र पृष्ठीय क्षेत्रफल / पार्श्व पृष्ठीय क्षेत्रफल) 

The area of the curved sides only (excluding the top and bottom circles).
  •  CSA = 2πrh

3. Total Surface Area (कुल पृष्ठीय क्षेत्रफल / संपूर्ण पृष्ठीय क्षेत्रफल)

The area of the curved side plus the areas of the top and bottom circular bases. 

 TSA = 2πr(r + h)

3 cone (शंकु)

  • Cone Formulas (शंकु के सूत्र)

    • Radius (r): Base radius

  • Slant Height (): =√ℎ²+(R-r)²

  • Curved Surface Area (CSA): π(R + r)l

  • Total Surface Area (TSA): TSA = π(R + r)l + π R² + π r² 

  • Volume 1/3πℎ(R²+r²+Rr)

  • 5 CUBE & CUBOID 

Cube (घन)

A cube has 6 equal square faces with side a

  • Volume (आयतन):  a³
  • Total Surface Area (कुल पृष्ठीय क्षेत्रफल): 6a² ,  6 × square of sides
  • Lateral Surface Area (पार्श्व पृष्ठीय क्षेत्रफल):  4a²
  • Diagonal (विकर्ण):  a√3
  • Perimeter (परिमाप): 12a 

Cuboid (घनाभ)

A cuboid is a 3D box with 6 rectangular faces. 

  • Volume (आयतन):  (L×B×H) here L is lenght , B is width , H is height 
  • Total Surface Area (कुल पृष्ठीय क्षेत्रफल): (2(lb + bh + hl))
  • Lateral Surface Area / Area of 4 walls (पार्श्व पृष्ठीय क्षेत्रफल): (2h(l + b))
  • Diagonal (विकर्ण): √(L²+B²+H²)

  • Perimeter (परिमाप): 4(l + b + h)

6 PYRAMID

  • Volume: (V = 1/3 × area of Base × height )

  • Lateral Surface Area (LSA): (LSA = 1/2 ×Perimeter of the base ×Slant height )
  • Total Surface Area (TSA): (TSA = B + 1/2×P×l)
  • Slant Height (l):  = √(h²+r²)

    • B = Area of the base (dependent on base shape, e.g., length × width for a rectangle)
    • h = Perpendicular height (vertical distance from the apex to the center of the base)
    • P = Perimeter of the base
    • l = Slant height (the height of the triangular side faces)

7 HEXAGONE

Angles and Diagonals

  • Interior Angle: Each interior angle is (120°)
  • Exterior Angle: Each exterior angle is (60°)
  • Number of Diagonals: 9

  •  Area Formula

    • Using side length : (A = 6 × √3/4 × a²
    • Using apothem (a): (A = 1/2 × perimeter × a

    • Perimeter Formula = 6 × a

      The perimeter  of a regular hexagon is the total length of its outer boundary