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jmc

geometry intermediate

Problem

Consider the rectangle with vertices at . How many integer coordinates will be strictly inside the rectangular region?
Solution
Points with integer coordinates are called lattice points. The length of the rectangle is units. There will be 9 lattice positions between the two vertical sides of the rectangle. The height of the rectangle is units. There will be 7 lattice positions between the top and bottom of the rectangle. That's a total of lattice points.
Final answer
63