Spherical Sector Calculator

Online calculator and formulas for calculating a spherical sector

The Spherical Sector - Cone-like section from the center!

Spherical Sector Calculator

The Spherical Sector

The spherical sector is a cone-like section from the center of a sphere to its surface.

Enter parameters
Select the known parameter
Value of the selected parameter
Radius of the original sphere
Spherical Sector Calculation Results
Segment height:
Segment radius:
Sphere radius:
Sector volume:
Cone surface:
Cap surface:
Sector surface:
Spherical Sector Properties

The spherical sector: Combination of spherical segment and cone

Cone-like From center Hybrid form Complete

Spherical Sector Visualization

Spherical Sector
The Spherical Sector

Cone-like section from the center

Complete section from the center.
Combination of segment and cone.

What is a spherical sector?

The spherical sector is a special geometric shape:

  • Definition: Cone-like section from the center of a sphere to its surface
  • Structure: Combination of spherical segment and cone
  • Completeness: Extends from center to sphere surface
  • Feature: Unites curved and straight surfaces
  • Application: Optics, geometry, architecture
  • Relationship: Extends the spherical segment to the center

Geometric properties of the spherical sector

The spherical sector shows hybrid geometric properties:

Basic parameters
  • Sphere radius r: Radius of the original solid sphere
  • Segment height h: Height of the spherical segment portion
  • Segment radius a: Radius of the circular cross-section
  • Center point: Starting point of the cone-like extension
Special properties
  • Hybrid form: Spherical segment plus cone surface
  • Complete section: From center to surface
  • Cone-like extension: Natural continuation to center
  • Rotational symmetry: Around the axis through the center

Mathematical relationships of the spherical sector

The spherical sector follows extended mathematical laws:

Volume formula
2π/3 × r² × h

The volume is proportional to r² and h. Simpler formula than the spherical segment.

Surface area formula
Cap: 2πrh + Cone: πar

The surface area combines spherical cap and conical surface.

Applications of the spherical sector

Spherical sectors find applications in various fields:

Optics & Photonics
  • Lens segments
  • Reflectors
  • Ray optics
  • Lighting technology
Geodesy & Navigation
  • Earth sphere sectors
  • Coordinate systems
  • Satellite navigation
  • Surveying technology
Architecture & Design
  • Special dome shapes
  • Modern architecture
  • Sculptural elements
  • Interior design
Mathematics & Physics
  • Volume calculations
  • Integral calculus
  • Geometric studies
  • Spatial geometry

Formulas for the spherical sector

Sector Volume (Vs)
\[V_s = \frac{2}{3} \cdot π \cdot r^2 \cdot h\]

Volume of the cone-like sector

Segment Height (h)
\[h = r - \sqrt{r^2 - a^2}\]

Height from sphere and segment radius

Segment Radius (a)
\[a = \sqrt{r^2 - (r - h)^2}\]

Radius of the circular cross-section

Sphere Radius (r)
\[r = \sqrt{(r - h)^2 + a^2}\]

Reconstruction of the sphere radius

Cap Surface Area (Sc)
\[S_c = 2 \cdot π \cdot r \cdot h\]

Curved surface area of the spherical cap

Cone Surface Area (SL)
\[S_L = π \cdot a \cdot r\]

Cone surface from center to cross-section

Sector Surface Area (S)
\[S = S_c + S_L = 2πrh + πar\]

Spherical cap plus cone surface

Important difference from spherical segment

The spherical sector corresponds to a spherical segment that, instead of the flat base surface, has a cone-like continuation to the center of the sphere. This creates a complete, closed shape from the center to the sphere surface.

Calculation example for a spherical sector

Given
Sphere radius r = 12 cm Segment height h = 5 cm Spherical sector

Find: All parameters of the spherical sector

1. Segment radius calculation

For r = 12 cm, h = 5 cm:

\[a = \sqrt{r^2 - (r - h)^2}\] \[a = \sqrt{144 - (12 - 5)^2}\] \[a = \sqrt{144 - 49} = \sqrt{95} ≈ 9.75 \text{ cm}\]

The segment radius is approximately 9.75 cm

2. Sector volume calculation

With r = 12 cm, h = 5 cm:

\[V_s = \frac{2π \cdot r^2 \cdot h}{3}\] \[V_s = \frac{2π \cdot 144 \cdot 5}{3}\] \[V_s = \frac{1440π}{3} = 480π ≈ 1507.96 \text{ cm}^3\]

The sector volume is approximately 1507.96 cm³

3. Cap surface calculation

With r = 12 cm, h = 5 cm:

\[S_c = 2π \cdot r \cdot h\] \[S_c = 2π \cdot 12 \cdot 5\] \[S_c = 120π ≈ 377.0 \text{ cm}^2\]

The cap surface is approximately 377.0 cm²

4. Cone surface calculation

With a ≈ 9.75 cm, r = 12 cm:

\[S_L = π \cdot a \cdot r\] \[S_L = π \cdot 9.75 \cdot 12\] \[S_L = 117π ≈ 367.6 \text{ cm}^2\]

The cone surface is approximately 367.6 cm²

5. Total surface calculation

Cap plus cone:

\[S = S_c + S_L\] \[S = 377.0 + 367.6\] \[S ≈ 744.6 \text{ cm}^2\]

The total surface area is approximately 744.6 cm²

6. Summary
r = 12.0 cm h = 5.0 cm a ≈ 9.75 cm
V ≈ 1507.96 cm³ S ≈ 744.6 cm²

The spherical sector with 5 cm segment height

7. Comparison with spherical segment
Spherical sector
V = 1507.96 cm³
Spherical segment (same h)
V ≈ 1272.35 cm³
Additional volume
≈ 235.61 cm³

The sector has about 18.5% more volume than the segment due to the cone

8. Geometric analysis
Height ratio
h/r = 5/12 ≈ 0.42
Radius ratio
a/r = 9.75/12 ≈ 0.81
Sector type
Medium height
Opening
Wide base

With h/r ≈ 0.42, a balanced spherical sector with wide opening is formed

The Spherical Sector: Complete cone geometry

The spherical sector is a fascinating geometric shape that combines the elegance of the spherical segment with the completeness of a cone-like extension to the center. As a complete section from the center of a sphere to its surface, it shows the perfect synthesis between spherical curvature and conical geometry. Its mathematical properties - with the elegant volume formula V = 2πr²h/3 and the hybrid surface calculation - make it an ideal example for complex three-dimensional geometry. The spherical sector demonstrates how extending a known form creates new, practically relevant shapes.

The geometry of completeness

The spherical sector shows the perfection of complete sections:

  • Cone-like extension: Natural continuation of the spherical segment to the center
  • Hybrid surface: Combination of spherical cap and cone surface
  • Complete shape: Closed form from center to surface
  • Elegant mathematics: Simpler volume formula than the spherical segment
  • Rotational symmetry: Perfect symmetry around the central axis
  • Scalable geometry: From pointed cone to wide sectors
  • Practical relevance: Important in optics, navigation and architecture

Mathematical elegance

Volume simplification

The volume formula V = 2πr²h/3 is more elegant than the spherical segment and shows direct proportionality to r² and h.

Surface hybridity

The combination of spherical cap (2πrh) and cone surface (πar) shows the dual nature of the sector.

Optical applications

In optics, spherical sectors enable precise beam guidance and light focusing through their cone-like geometry.

Geodetic significance

In geodesy, spherical sectors help calculate earth sphere sections and coordinate systems.

Summary

The spherical sector embodies the perfect completion of the spherical segment through its cone-like extension to the center. As a complete section from the center of a sphere to its surface, it unites the natural elegance of spherical curvature with the constructive clarity of conical geometry. Its mathematical properties - from the simplified volume formula to the hybrid surface calculation - demonstrate the beauty of extending geometry. From optical applications in lighting technology to geodetic calculations in surveying technology to architectural special solutions, the spherical sector shows its versatile applicability. It connects the purity of geometric forms with the functionality of complete shapes and remains an impressive example of the power of mathematical extensions in three-dimensional geometry.