## Revision Notes for Ch 12 Areas related to Circles Class 10th Mathematics

**Area of Sector**

__Sector:__Sector of a Circle is given as part of Circle enclosed by 2 radius and arc.

In the diagram, shaded area OAB is the sector.

Here, Î¸ is the angle subtended by the arc AB on the center O of the circle.

Semi-Circle is a sector forming an angle 180Â° with center.

Î¸=180Â°

Now, Area of Semi Circle will be given as

Segment is defined as area enclosed by chord and arc of the circle.

â€¢ It is the length which enclosed the sector.

â€¢ Length of arc AB + OA + OB.

â€¢ OA=OB=r, that is radius of sector.

So,

**Area of Semi Circle**Semi-Circle is a sector forming an angle 180Â° with center.

Î¸=180Â°

Now, Area of Semi Circle will be given as

**Area of Quarter Circle****Area of Segment**

Segment is defined as area enclosed by chord and arc of the circle.

**Perimeter of Sector**

â€¢ It is the length which enclosed the sector.

â€¢ Length of arc AB + OA + OB.

â€¢ OA=OB=r, that is radius of sector.

So,