Final answer:
The perimeter of a rectangle with a width of 12 cm and length twice the width is 72 cm.
Step-by-step explanation:
The perimeter of a rectangle is calculated as P = 2l + 2w, where l is the length and w is the width of the rectangle. Given that the width w is 12 cm and the width is half the length, we can express the length as l = 2w.
Substituting w = 12 cm into the expression for length, we get l = 2 × 12 cm = 24 cm.
Now we can calculate the perimeter using the formula: P = 2l + 2w = 2 × 24 cm + 2 × 12 cm
= 48 cm + 24 cm
= 72 cm.
So the perimeter of the rectangle is 72 cm.