Final answer:
To find the length of each side of the rectangle, we can use the formula for the perimeter and the given relationship between the length and width. By solving the equation, we find that the width is 7 cm and the length is 14 cm.
Step-by-step explanation:
To find the length of each side of the rectangle, we need to use the information given. The problem states that the length of the rectangle is twice its width. Let's assume the width is w, then the length would be 2w. The perimeter of a rectangle is given by the formula P = 2(L + W), where P is the perimeter, L is the length, and W is the width.
So, for our rectangle, we have 42 = 2(2w + w). Simplifying this equation, we get 42 = 2(3w), which gives us 42 = 6w. Dividing both sides by 6, we find that w = 7.
Therefore, the width of the rectangle is 7 cm, and the length is twice that, or 14 cm.