In geometry, the area enclosed by a circle of radius r is πr2. Here the Greek letter π represents the constant ratio of the circumference of any circle to its diameter, approximately equal to 3.1416.

To calculate arc length without the angle, you need the radius and the sector area:

1. Multiply the area by 2.
2. Then divide the result by the radius squared (make sure that the units are the same) to get the central angle in radians.

Area of a sector Now the area of the sector for the above figure can be calculated as (1/8) (3.14×r×r).

An arc of a circle is any portion of the circumference of a circle. To recall, the circumference of a circle is the perimeter or distance around a circle. Therefore, we can say that the circumference of a circle is the full arc of the circle itself.

In general, an arc is any smooth curve joining two points. The length of an arc is known as its arc length. The center of an arc is the center of the circle of which the arc is a part. An arc whose endpoints lie on a diameter of a circle is called a semicircle.

To avoid confusion, major arcs are usually named with the words “major arc” and two letters or the word “arc” and three letters. For example major arc(BC) and arc(BAC) both refer to the major arc shown in the illustration above. A semicircle is half of a circle.

Arc: An arc is the part of circumference. DFE is the arc of the circle. Sector: Sector is an interior region bounded by pair of radii and arc on one side. OBC is a sector of the circle where OB and OC are radius and BC is an arc. Segment: Segment is an interior region bounded by a chord and an arc.

Types of arc welding

• Shielded metal arc welding.
• MAG welding.
• MIG welding.
• Electrogas arc welding (EGW)