Tag: circle and its elements

Sector is the region between an arc and two radii joining. The centre to the end points of the arc.

$\begin{array}{l} Area\, of\, a\, \sec  tor\, =\dfrac { 1 }{ 2 } { r^{ 2 } }\theta  \ =\dfrac { 1 }{ 2 } \times r\times r\theta  \ =\dfrac { 1 }{ 2 } \times r\times l \ Hence,\, option\, A\, is\, \, the\, \, correct\, \, answer. \end{array}$

Segment is the region between the chord and its corresponding arc.

False.
The region between an arc and the two radii, joining the centre to the end points of the arc is called a sector

Area of sector formed from angle $\theta=\dfrac{\theta}{360^\circ}\pi r^2$, where $r$ is the radius of the circle
Now, if angle is $120^\circ$, $150^\circ$ then the ratio of area of sector will be

The region between an arc and two radii joining the center to the end points of the arc is called sector.The minor are corresponds to minor sector  and  major arc correspond to major sector.

By inscribed angle theorem, 

Pizza slice, Cathedral window and apple pie are sector of a circle 

A circular dome is a 3 dimension structure of a semicircle.