Final answer:
To find the area of a square, square the length of one side.
Step-by-step explanation:
To calculate the area of a square, you need to know the length of one side. In this case, the height given is actually the length of one side of the square. Since all sides of a square are equal, the area can be found by squaring the length of one side. So, if the height is 15 mm, the area of the square would be 15 mm x 15 mm = 225 mm².
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