**The formula to find the area of a sector is A = N/360 x (pi x r^2).** A sector is a section of a circle. In the formula given, A is the area of the sector, N is the degree of the central angle of the sector, pi is an irrational number that can be rounded to 3.14, and r is the length of the radius of the circle.

Certain information needs to be available to use the formula and find the area. The first thing that needs to be known is the degree of the central angle of the sector. The central angle is created at the point in the center of the circle where the two radii that mark the edges of the sector meet. The length of the radius of the circle also needs to be known to solve for the area of the sector.

If the radius of the circle is 10 inches, and the central angle of the sector is 90 degrees, the area of the sector can be found as follows: 90/360 * (3.14 * 10^2). Following the order of operations, the equation proceeds as follows: 1/4 * (3.14 * 100) = 1/4 * 314 = 78.5. Thus, the area of the sector is 78.5 square inches.