1972 AHSME Problems/Problem 28
A circular disc with diameter is placed on an checkerboard with width so that the centers coincide. The number of checkerboard squares which are completely covered by the disc is
Consider the upper right half of the grid, which consists of a section of the checkerboard and a quarter-circle of radius . We can draw this as a coordinate grid and shade in the complete squares. There are squares in the upper right corner, so there are whole squares in total.
The answer is
-edited by coolmath34