Find the area A of the sector of a circle of radius 30 feet formed by the central angle 
radian.
Solution:-
A central angle is an angle whose vertex is at center of a circle.
The rays of a circle angle subtend an arc on the circle. The part of the circle between the rays of the angle and the arc subtended is called a sector. We have the following theorem.
Area of a Sector
The area A of a sector of a circle of radius r formed by a central angle of 
radians is
A = 
The value of r in the formula is 30 feet.
The value of in the formula is radian.
Therefore,
A (area) = 
= 34.615 
.