First find the area of the sector of 150 degrees:
150/360 x PI * 27.8^2 = 1011.6452 in^2
Now find the area of the triangle formed by the 150 degrees and the radius 27.8
first find the length of the chord ( the base of the triangle)
c^2 = 27.8^2 + 27.8^2 - 2 * 27.8 * cos(150) = 53.71
now find the height by using half the chord length as the base and using the Pythagorean theorem:
26.855^2 - 27.8^2 = height^2
height = 7.19
The area of the triangle is 1/2 x base x height = 1/2 x 26.855 x 7.1952 = 96.605
multiply by 2 because we made 2 right triangles: 96.54 x 2 = 193.21 square inches.
Now the area of the shaded region is the area of the sector minus the area of the triangle:
1011.6452 - 193.21 = 818.4352
Rounded to nearest tenth = 818.4 in^2