The portion of the circle and its interior that is formed by the two radii
enclosing a central angle and an arc is called a sector of the circle. The formula
for the area of a circular sector in terms of the radius r of the circle and the
central angle θ, measured in radians, is area = r
2
θ.
To enter this formula in the calculator, access the SOLVER by pressing
2ndF SOLVER . Press CL to delete any equation that appears on the screen.
Type in the equation A= R
2
θ by pressing ALPHA A ALPHA = 1
a/b 2 ALPHA R x
2
ALPHA θ .
Consider this problem situation. A lawn sprinkler is set so that the region of the
lawn that is watered is approximately a sector of a circle of radius 6 feet. If the
central angle of the sector is radians, find the area of the region that is
watered by the sprinkler.
48 Area of a Circular Sector/TRIGONOMETRY USING THE SHARP EL-9600
1
2
π
5
π
5
6 ft
6 ft
1
2
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