Final answer:
The provided question lacks sufficient details to find the area of a square based on the given perimeters of a triangle and rectangle, none of the given choices matches a square with a perimeter of 30 cm.
Step-by-step explanation:
The question doesn't provide enough information to determine the side length of the square based on the perimeters of the triangle and the rectangle alone, since we know their perimeters are 30 cm but not their side lengths. However, we can use the fact that the perimeter of a square is 4 times the length of one side to find the area. If we consider the options given, each side of the square would be the square root of the area. So for the areas given (a) 36, (b) 49, (c) 64, and (d) 81 square cm, the side lengths would be 6, 7, 8, and 9 cm respectively. Therefore, the perimeters would be 24, 28, 32, and 36 cm. The only option that gives a perimeter of 30 cm is not listed, so based on the given information and options, we cannot find a matching square that fulfills the criterion of having both a perimeter and area from the given choices.