## 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, θ is the angle subtended by the arc AB on the center O of the circle.

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

θ=180°

Now, Area of Semi Circle will be given as

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

• It is the length which enclosed the sector.

• Length of arc AB + OA + OB.

• OA=OB=r, that is radius of sector.

So,

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

θ=180°

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**

• It is the length which enclosed the sector.

• Length of arc AB + OA + OB.

• OA=OB=r, that is radius of sector.

So,