To calculate the area of a square with an area of 490 mm², one must determine the length of each side, which is found by taking the square root of the area. The square root of 490 mm² is approximately 22.14 mm. The discussion reveals confusion regarding the shape in question, as the provided image may not accurately represent a square. Clarification is needed on the dimensions and shape being analyzed. Ultimately, understanding the basic geometric principles is essential for calculating area correctly.