Answer:
6 cm
Step-by-step explanation:
Let the smaller square have side of x then the larger square has side 2x
Sum the areas of the 2 squares and equate to 45
x² + (2x)² = 45
x² + 4x² = 45
5x² = 45 ( divide both sides by 5 )
x² = 9 ( take the square root of both sides )
x = = 3
side of smaller square = 3 cm
side of larger square = 2 × 3 = 6 cm
check : 3² + 6² = 9 + 36 = 45 cm² ← correct