Measure and calculate the perimeter of composite rectilinear shapes in centimetres and metres - Reasoning

The task involves calculating the perimeter of a composite shape composed of 12 identical squares, each with an area of 49 cm². To determine the perimeter, one must first ascertain the length of a side of a single square. Since the area of a square is found by squaring the length of one side (side x side), and we know that the area is 49 cm², it can be deduced that the length of one side is the square root of 49 cm², which is 7 cm. With this information, the perimeter of the entire composite shape can be calculated.

To find the total perimeter of the composite shape, we need to consider the number of sides that contribute to the perimeter. Given that the shape has 40 sides in total, and each side measures 7 cm, the perimeter can be calculated by multiplying the length of one side by the total number of sides. Therefore, the perimeter of the composite shape is 7 cm multiplied by 40, which equals 280 cm. This calculation assumes that all external sides are counted once and that internal sides, where two squares meet, are not included in the perimeter measurement, as they do not contribute to the external boundary of the shape.