Well the area of a sector formula is: A = (degree/360) × πr² We know the degree so keep that in mind. The diameter is 15 the radius is half of the diameter so the radius is 7.5. Now we plug these into the equation: A = (180/360) × π7.5² A= (1/2) × π56.25 A= 28.125 × π A = 28.125π