A rectangular picture has dimensions 2 1/2 by 1 1/2. It is to be enlarged so that it is still similar to the original rectangle. If the longer dimension is now 10 , how much longer than the original is the perimeter now

Respuesta :

The original perimeter is:
 p = 2 (w) +2 (l)
 First we look for the scale factor of the longest dimension, which is given by:
 k = (10) / (2 1/2)
 k = 4
 Then, the perimeter is given by:
 p '= 2 (4w) +2 (4l)
 Rewriting:
 p '= 4 (2 (w) +2 (l))
 p '= 4p
 Answer:
 
the perimeter now is 4 times longer than the original