Parts of a Circle

A circle is an enclosed round figure whose centre is equidistant from its boundary at every point. Its locus is defined in such a way that it remains constant throughout the distance along the circle. Some parts of a circle are located inside the circle, like diameter, radius, chord, segment; some are located outside the circle, like secant, tangent, arc, and some are located on the circle, like sector, circumference. A circle has the following parts-

• Centre – The centre of a circle is a fixed point inside a circle that is equidistant from the circle's boundary. If we move a thread or compass from the centre to the boundary, then the distance will be the same, denoting the centre of the circle is correct. If the distance is not the same, then the centre must be misaligned.
• Radius – The circle's radius is half the distance from one boundary to another, passing through the centre. It is generally denoted by r.
• Diameter – The distance from one end of a circle to another passing through the centre of the circle is known as diameter. It is denoted by d. It is equal to twice the radius, i.e. d = 2r.
• Circumference – The total boundary of the circle is known as its circumference. The circumference is the perimeter of the circle. The formula to calculate the circumference of a circle is 2πr, where r is the circle's radius. It can be written as πd, as 2r = d, where d is the circle's diameter.
• Tangent – The tangent of a circle is an exterior line that passes just touching the circle's boundary. The tangent must touch the boundary only at one place. No tangent in a circle ever intersects each other. If it intersects, then it is not a tangent.
• Secant – Secant is a line that crosses through a circle. It should pass entirely from one end of a circle to another. If it stays only inside, then it is called a chord. If it passes through the centre, then it is referred to as the diameter.
• Chord – A chord is a line segment joining two ends of a circle. A circle can have an infinite number of chords. Diameter is the largest chord present in the circle.
• Arc – The outer circumference of the circle cut by a secant is known as an arc. An arc is a part of a circle, if extended, will produce a complete circle again.
• Segment – When the circle is cut into two unequal parts, two segments are formed. The more significant part is the major segment, and the smaller part is the minor segment. The circle can be cut by a secant or a chord, or even a diameter.
• Sector – A sector is a part of the circle bounded by two radii and the circle's circumference. It is a fractional part of a complete circle.