Question

A 5-in. by 8-in. photo is enlarged by a scale factor of 1 in. : 2 in.

a. Find the perimeter and area of the enlarged postcard.

b. Suppose the length and width of the enlarged postcard is doubled. Describe how the perimeter and area are affected.

c. Suppose the width of the enlarged photograph is doubled. Describe how the perimeter and area are affected.

Answer 1

(a) each side is doubled; so the perimeter is also.
(b) perimeter is doubled again. Since area is length*width, the area is multiplied by 2^2.
(c) if only the length is doubled, the perimeter is increased, but not doubled.
2(w + 2L) = 2w + 4L. The area is doubled, since (w)(2L) = 2(wL) = 2A

Answer 2

(a) each side is doubled; so the perimeter is also.
(b) perimeter is doubled again. Since the area is length*width, the area is multiplied by 2^2.
(c) if only the length is doubled, the perimeter is increased, but not doubled.
2(w + 2L) = 2w + 4L. The area is doubled, since (w)(2L) = 2(wL) = 2A