SOLUTION: an american flag measures 20 inches by 8 inches. What are the dimensions of an american flag with four times the area of the original flag and its dimensions in the same proportio

Algebra ->  Rectangles -> SOLUTION: an american flag measures 20 inches by 8 inches. What are the dimensions of an american flag with four times the area of the original flag and its dimensions in the same proportio      Log On


   

Question 183666: an american flag measures 20 inches by 8 inches. What are the dimensions of an american flag with four times the area of the original flag and its dimensions in the same proportion as the original flag?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
8%2F20+=+2%2F5
A%5B1%5D+=+20%2A8 in2
A%5B1%5D+=+160 in2
A%5B2%5D+=+4%2A160 in2
A%5B2%5D+=+640 in2
Let the dimensions of the new flag = a and b
a%2Fb+=+2%2F5
multiply both sides by 5b
5a+=+2b
a+=+%282%2F5%29%2Ab
A%5B2%5D+=+a%2Ab
A%5B2%5D+=+%282%2F5%29%2Ab%2Ab
640+=+%282%2F5%29%2Ab%5E2
b%5E2+=+%285%2F2%29%2A640
b%5E2+=+1600
b+=+40
and, since
a+=+%282%2F5%29%2Ab
a+=+%282%2F5%29%2A40
a+=+16
The dimensions of the new flag are 40 in by 16 in