How many different rectangles? - Answers

To determine how many different rectangles can be formed, you need to know the number of horizontal and vertical lines available. The formula for calculating the number of rectangles is based on choosing two horizontal lines and two vertical lines from the grid. If there are ( m ) horizontal lines and ( n ) vertical lines, the total number of rectangles is given by the combination formula: ( \binom{m}{2} \times \binom{n}{2} ). This accounts for all possible pairs of lines that can create a rectangle.