First find the area of the entire pizza.
Area of circle: [tex] \pi r^2 [/tex]
Plug 9 in for the radius (radius = diameter/2).
[tex] \pi 9^2 [/tex] = 254.47 in²
Divide the area of the entire pizza by 10 slices.
254.47/10 = 25.447
Each slice is 25.447 inches² (or 8.1pi).
