Find a rule that represents the number of tiles in Figure
The red circles point out the left arms,
the green circles point out the rectangles,
and the blue circles point out the right arms.
Notice the following:
The length of the rectangle in Figure 1 is 3 units × 2 units;
the rectangle in Figure 2 is 4 units × 3 units;
and the rectangle in Figure 3 is 5 units × 4 units.
First, look at the left arm. It remains constant in each of these figures, with a value of
There is a rule for the size of the rectangles:
Now, consider the right arms. Its length matches its corresponding figure number.