- 1. Basic Concepts of Prepared By Ronnith Nandy
- 2. Circle is a simple shape of Euclidean geometry that is the set of points in the plane that are equidistant from a given point, the centre. A circle is a simple closed curve which divides the plane into 3 regions: Interior, Exterior and On In everyday use, the term "circle" may be used interchangeably to refer to either the boundary of the figure, or to the whole figure including its interior; in strict technical usage, the circle is the former and the latter is called a disk.
- 3. The word "circle" derives from the Greek, kirkos "a circle," from the base Ker- which means to turn or bend. Circle was created long before recorded history. It is quite likely that it was drawn by a stick in the sand. With the sun being a constant in early man’s existence and the source of all life, it is quite likely that the first circle represented the sun. Circle has evolved substantially with Euclidean geometry being its crowning point of technological understanding, Without circles, there would be no wheel, which is man’s crowning achievement dating back to the Neolithic Age (circa 9500 BC).
- 4. Parts of a Circle
- 5. CIRCLE TERMINOLOGY CIRCUMFERENCE The Circumference of a circle (from "circa", the Latin word for "around") is the distance around the edge of the circle.
- 6. CIRCLE TERMINOLOGY RADIUS In classical geometry, the radius of a circle or sphere is the length of a line segment from its center to its perimeter. The name comes from Latin radius, meaning "ray" but also the spoke of a chariot wheel.
- 7. CIRCLE TERMINOLOGY CHORD A chord of a circle is a straight line segment whose endpoints both lie on the circle. A secant line, or just secant, is the infinite line extension of a chord. More generally, a chord is a line segment joining two points on any curve, for instance an ellipse.
- 8. CIRCLE TERMINOLOGY DIAMETER The diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle.
- 9. CIRCLE TERMINOLOGY ARC The arc of a circle is a portion of the circumference of a circle. Measure an arc by two methods: 1) the measure of the central angle or 2) the length of the arc itself.
- 10. CIRCLE TERMINOLOGY SEGMENT The segment of a circle is the region bounded by a chord and the arc subtended by the chord.
- 11. CIRCLE TERMINOLOGY SECTOR A circular sector or circle sector (symbol: ⌔), is the portion of a disk enclosed by two radii and an arc, where the smaller area is known as the minor sector and the larger being the major sector.
- 12. PROPERTIES OF CIRCLE In geometry, a large number of facts about circles and their relations to straight lines, angles and polygons can be proved. These facts are called the properties of the circle. Circles having equal radii are congruent. Circles having different radii are similar. The central angle which intercept an arc double of any inscribed angle that intercepts the same arc. The radius perpendicular to a chord bisects the chord. The chords equidistant from the center are equal in length. A tangent to a circle is at right angles to the radius at the point of contact. Two tangents drawn to a circle from a point out side are equal in length. The angle subtended at the center of a circle by its circumference is equal to four right angles.
- 13. PROPERTIES OF CIRCLE In geometry, a large number of facts about circles and their relations to straight lines, angles and polygons can be proved. These facts are called the properties of the circle. Circumference of two different circles is proportional to their corresponding radii. Arcs of the same circle are proportional to their corresponding angles. Radii of the same circle or the equal circles are equal. Equal chords have equal circumferences. The diameter of a circle is the longest chord. Circle which have equal radii are equal. Equal circles have equal circumference.