Final answer:
The length of one side of a square painting with an area of 25 square feet is 5 feet, because 5 × 5 equals 25 square feet.
Step-by-step explanation:
The student's question asks, "What will the length of one side of the painting measure if the area of the painting is 25 square feet?" To find the length of one side of a square when we know the area, we take the square root of the area because the area of a square is found by squaring the side (Area = side × side). Since the area is given as 25 square feet, we look for a number that, when multiplied by itself, equals 25.
The number that fits this condition is 5 because 5 × 5 = 25. So, the length of each side of the painting is 5 feet. Therefore, the answer to the question is (a) 5 feet.