We know that the diameter is 16 inches. The radius will ALWAYS be equal to half of the diameter! 16/2 is 8, so r=8.
Now we can use the formula. 8^2 is 64, an 64pi is about 201. 201 is the area of the entire pizza.
Because we are only looking for the area of one slice, we can put 201 over 12, which is about 16.74.
Therefore, the area for one slice is 16.74 square inches.