The area of O is 92pi. The area of the shaded sector must be equal to the size of the sector. the sector is 90 degrees or 1/4 of the circle. Find the area of the shaded sector.
If the area of the entire circle is 92 pi and 1/4 of it is a shaded sector. the the shaded area is 1/4 * 92 pi = 23 pi units^2