Yes
In general, if the dimensions of any two similar shapes are in the ratio m:n , then their areas are in the ratio m2:n2 .
In your case, two similar pizzas (whether circular, rectangular, or what have you) whose dimensions are in the ratio 1:1 have their areas in the ratio 2:1 . Thus, one 12 inch pizza has the same amount of pizza as two 6 inch pizzas.
I think this answer might help you
