To warn ships for underwater rocks, a lighthouse spreads a red colored light over a sector of angle80° to a distance of 16.5 km. Find the area of the sea over which the ships are warned. (Use π = 3.14)
It can be seen from the figure that the lighthouse spreads light across a sector of 80° in a circle of 16.5 km radius
Area of sector OACB =
* 
r2
= 
* 3.14 * 16.5 * 16.5
= 189.97 km2
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