Answer:
- 258 ft² (first attachment)
- 282 ft² (second attachment)
Explanation:
You want the area of an L-shaped rectilinear figure with overall dimensions of 18 ft high and 21 ft wide, and a cutout that is 12 ft wide. The dimension of the "right side of the figure" is given as 8 ft.
Difference of areas
The area of such a figure can be found as the difference between the overall area and the area of the rectangle cutout at upper right. The overall area is ...
A = LW
A = (18 ft)(21 ft) = 378 ft²
Missing corner
If the lower right-side dimension is 8 ft, as in the first attachment, then the rectangle cutout is 10 ft by 12 ft, for an area of ...
cutout = (10 ft)(12 ft) = 120 ft²
The area of the L-shaped figure in the first attachment is ...
378 ft² -120 ft² = 258 ft² . . . . . . area of L-shape (first attachment)
The problem statement is ambiguous as to which right-side dimension is 8 ft. If that is the vertical dimension of the right side of the "vertical rectangle", then the dimensions are those of the second attachment. The cutout area is 8 ft by 12 ft, or 96 ft².
This L-shaped area is ...
378 ft² -96 ft² = 282 ft² . . . . . . . area of L-shape (second attachment)