Problem
COM-B1-M01-P020 Rectangles in a Grid
#20
★★★☆☆ Level 3 of 5
How many rectangles can be chosen in a \(4\) by \(5\) grid of cells?
A rectangle is determined by two vertical and two horizontal grid lines.
A \(4\) by \(5\) grid has \(5\) horizontal and \(6\) vertical grid lines. Choose \(2\) vertical and \(2\) horizontal lines: \(15\cdot10=150\).
Classic problem on choosing boundaries.