we know that
Area of a regular polygon = (1/2)*apothem*perimeter
perimeter of the regular decagon=10*a
where
a is the length side of the decagon
in this problem
a=1.8 ft
so
perimeter of the regular decagon=10*1.8----> 18 ft
Area of a regular decagon = (1/2)*2.8*18----> 25.2 ft²
Round to the nearest whole number------> 25 ft²
the answer is
25 ft²
