Answer:
51 ft²
Step-by-step explanation:
The shaded area is the area of the triangle subtract the area of the rectangle.
The area (A) of the triangle is calculated as
A = bh ( b is the base and h the perpendicular height )
Here b = 11 and h = 10, thus
A = 0.5 × 10 × 11 = 5 × 11 = 55 ft²
Area of rectangle = 1 × 4 = 4 ft², hence
Area of shaded region = 55 - 4 = 51 ft²