Illustration of circle with sector and segment used to find area.

Circle With Sector and Segment labeled

Illustration of circle with sector and segment used to find area.

Illustration of partial circle with sector and segment used to find area.

Circle With Sector and Segment labeled

Illustration of partial circle with sector and segment used to find area.

Illustration of a circle with a sector. "A sector of a circle is the space included between an arc and two radii drawn to the extremities of the arc."

Sector of Circle

Illustration of a circle with a sector. "A sector of a circle is the space included between an arc and…

Illustration of a sector of a circle. A sector is the space between an arc and two radii drawn to the extremities of the arc.

Sector Of Circle

Illustration of a sector of a circle. A sector is the space between an arc and two radii drawn to the…

Illustration of a sector of a hollow circle. A sector is the space between an arc and two radii drawn to the extremities of the arc.

Sector Of A Hollow Circle

Illustration of a sector of a hollow circle. A sector is the space between an arc and two radii drawn…

Illustration of a circle with 6 equal sectors.

Sectors of Circle

Illustration of a circle with 6 equal sectors.

Illustrations of a circle with segment, semicircle, sector, quadrant, and central angles drawn.

Circle with Segment, Semicircle, Sector, Quadrant, and Central Angle

Illustrations of a circle with segment, semicircle, sector, quadrant, and central angles drawn.

"Fixed Conensing Light for a Single Sector, 1850.—The holophote Light pLp throws its whole light on straight condensing prisms c, each of which distributes the rays over the required sector." —The Encyclopedia Britannica, 1910

Condensing Light

"Fixed Conensing Light for a Single Sector, 1850.—The holophote Light pLp throws its whole light…

"Used with indistinct or invisible targets and to define sectors." — Moss, 1914

Finger system

"Used with indistinct or invisible targets and to define sectors." — Moss, 1914

Illustration of an angle &alpha with the vertex at the center, O, of a circle with radius OB. AC and BD are perpendicular to OB and join B with C. The are of the triangle OBC is less than the are of the sector OBC, and the sector OBC is less than the triangle OBD.

Triangles and Sectors in Quadrant I

Illustration of an angle &alpha with the vertex at the center, O, of a circle with radius OB. AC and…

The sector is a hinged rule with scales used for various mathematical calculations.

Sector

The sector is a hinged rule with scales used for various mathematical calculations.

"In geometry: (a) A plane figure inclosed between the arc of a circle, ellipse, or other central curve and two radii to its extremities from the center. Thus, in the figure, CDB is a sector of a circle." -Whitney, 1911

Sector

"In geometry: (a) A plane figure inclosed between the arc of a circle, ellipse, or other central curve…

An illustration showing a circle sector with radius r, center/central angle v, and length of circle arc b.

Circle Sector

An illustration showing a circle sector with radius r, center/central angle v, and length of circle…

An illustration showing a circle sector with center/central angle v and polygon angle w.

Circle Sector

An illustration showing a circle sector with center/central angle v and polygon angle w.

An illustration showing a circle sector with height of segment h and radius r.

Circle Sector

An illustration showing a circle sector with height of segment h and radius r.

Diagram of a sphere with sectors and arcs drawn.

Sphere With Sectors and Arcs

Diagram of a sphere with sectors and arcs drawn.

Illustration of a sphere with sectors and arcs.

Sphere With Sectors and Arcs

Illustration of a sphere with sectors and arcs.

Illustration of a right spherical triangle and the five circular parts placed in the sectors of a circle in the order in which they occur in the triangle. "The ten formulas used in the solution of spherical right triangles can be expressed by means of two rules, known as Napier's rules of circular parts."

Napier's Right Spherical Triangle

Illustration of a right spherical triangle and the five circular parts placed in the sectors of a circle…

Illustration used, with the law of sines, to find the relation between two sides of a spherical triangle and the angles opposite.

Relationships In A Spherical Triangle

Illustration used, with the law of sines, to find the relation between two sides of a spherical triangle…

Illustration used, with the law of cosines, to find the relation between the three sides and an angle of a spherical triangle.

Relationships In A Spherical Triangle

Illustration used, with the law of cosines, to find the relation between the three sides and an angle…

Illustration used to extend the law of cosines when finding the relation between the three sides and an angle of a spherical triangle. In this case both angles b and c are greater than 90°.

Relationships In A Spherical Triangle

Illustration used to extend the law of cosines when finding the relation between the three sides and…

Illustration used to extend the law of cosines when finding the relation between the three sides and an angle of a spherical triangle. In this case angle b<90&deg; and angle c>90&deg;.

Relationships In A Spherical Triangle

Illustration used to extend the law of cosines when finding the relation between the three sides and…

Illustration of a right spherical triangle with a and b the sides, and &alpha; and &beta; the angles opposite them. Side c is the hypotenuse.

Right Spherical Triangle

Illustration of a right spherical triangle with a and b the sides, and α and β the angles…

Diagram showing 2 superimposed symmetrical spherical triangles.

Superimposed Symmetrical Spherical Triangles

Diagram showing 2 superimposed symmetrical spherical triangles.

Diagram showing 2 symmetrical spherical triangles.

Symmetrical Spherical Triangles

Diagram showing 2 symmetrical spherical triangles.

An illustration showing a circle with sectors D and E inscribed in a triangle with angles, A, B, and C.

Circle Inscribed In A Triangle

An illustration showing a circle with sectors D and E inscribed in a triangle with angles, A, B, and…

Diagram showing a spherical triangle.

Spherical Triangle

Diagram showing a spherical triangle.

Diagram showing a spherical triangle constructed by the intersection of polar arcs.

Spherical Triangle

Diagram showing a spherical triangle constructed by the intersection of polar arcs.

Diagram showing a spherical triangle constructed by the intersection of polar arcs.

Spherical Triangle

Diagram showing a spherical triangle constructed by the intersection of polar arcs.

Diagram showing a spherical triangle constructed by the intersection of polar arcs.

Spherical Triangle

Diagram showing a spherical triangle constructed by the intersection of polar arcs.

Diagram showing a 2 symmetrical spherical triangles.

Two Symmetrical Spherical Triangles

Diagram showing a 2 symmetrical spherical triangles.