The diagonal of the first square is 42 cm.
For any square with side length a, the diagonal is a2 and the area is a2.
Let the side of the first square be a.
Diagonal = a2
42=a2
a=242
a=4 cm
Area of the first square:
Area = a2
Area = (4)2
Area = 16 cm²
The second square has double the area:
Area of second square = 2×16
Area of second square = 32 cm²
Let the side of the second square be b.
b2=32
b=32
b=16×2
b=42 cm
The diagonal of the second square:
Diagonal = b2
Diagonal = 42×2
Diagonal = 4×2
Diagonal = 8 cm
The diagonal of the second square is 8 cm.