1)we calculate the area of the circle
area of a circle=r²π
Data:
radius=18 in
area of this circle=(18 in)²π=324π in².
2)we calculate the measure of the central angle with area equal 162π in².
324π in²----------------------360º
162π in²---------------------- x
x=(162π in² * 360º) / 324π in²=180º
Answer: 180º.