SOLUTION: The altitude of a rectangle is 20% less than the base and the perimeter is 18cm.Find the dimensions of the rectangle

Algebra ->  Rectangles -> SOLUTION: The altitude of a rectangle is 20% less than the base and the perimeter is 18cm.Find the dimensions of the rectangle      Log On


   

Question 1077822: The altitude of a rectangle is 20% less than the base and the perimeter is 18cm.Find the dimensions of the rectangle
Found 2 solutions by josmiceli, josgarithmetic:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let the altitude = +a+ cm
Let the base = +b+ cm
------------------------
(1) +a+=+b+-+.2b+
(1) +a+=+.8b+
and
(2) +2a+%2B+2b+=+18+
----------------------
(2) +a+%2B+b+=+9+
Plug (1) into (2)
(2) +.8b+%2B+b+=+9+
(2) +1.8b+=+9+
(2) +b+=+5+
and
(1) +a+=+.8b+
(1) +a+=+.8%2A5+
(1) +a+=+4+
The rectangle is 4 x 5
-----------------------
check:
(2) +2a+%2B+2b+=+18+
(2) +2%2A4+%2B+2%2A5+=+18+
(2) +8+%2B+10+=+18+
(2) +18+=+18+
OK

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
x, base of rectangle
x-x%2F5, altitude of rectangle


x-x%2F5=5x%2F5-x%2F4=4x%2F5

highlight_green%282%28x%29%2B2%284%2F5%29x=18%29

-
x%2B4x%2F5=9
5x%2B4x=45
9x=45
highlight%28x=5%29
-
altitude is %284%2F5%29x=%284%2F5%29%2A5=highlight%284%29.