SOLUTION: The diagonal of a rectangular room is 13 ft long. One wall measures 7 ft longer than the adjacent wall. Find the dimensions of the room. The width of the room is? The length of

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: The diagonal of a rectangular room is 13 ft long. One wall measures 7 ft longer than the adjacent wall. Find the dimensions of the room. The width of the room is? The length of      Log On


   



Question 1086769: The diagonal of a rectangular room is 13 ft long. One wall measures 7 ft longer than the adjacent wall. Find the dimensions of the room.
The width of the room is?
The length of the room is?

Found 2 solutions by MathLover1, josmiceli:
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

let one wall be a,the adjacent wall b, and diagonal c
if the diagonal of a rectangular room is 13ft long: c=13ft
One wall measures 7ft longer than the adjacent wall:a=b%2B7ft
since they form right angle triangle, use Pythagorean theorem:
c%5E2=a%5E2%2Bb%5E2
%2813%29%5E2=%28b%2B7ft%29%5E2%2Bb%5E2....solve for b
169=b%5E2%2B14b%2B49%2Bb%5E2
2b%5E2%2B14b%2B49-169=0
2b%5E2%2B14b-120=0...simplify
b%5E2%2B7b-60=0...factor
b%5E2%2B12b-5b-60=0
%28b%5E2%2B12b%29-%285b%2B60%29=0
b%28b%2B12%29-5%28b%2B12%29=0
%28b+-+5%29%28b+%2B+12%29+=+0
we need only positive solution:
%28b+-+5%29+=+0=>highlight%28b=5ft%29
now find a
a=5ft%2B7ft
highlight%28a=12ft%29

The width of the room is highlight%285ft%29.
The length of the room is highlight%2812ft%29.


Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let the shortest wall = +x+
The longer wall = +x+%2B+7+
----------------------------
+x%5E2+%2B+%28+x%2B7+%29%5E2+=+13%5E2+
+x%5E2+%2B+x%5E2+%2B+14x+%2B+49+=+169+
+2x%5E2+%2B+14x+-+120+=+0+
+x%5E2+%2B+7x+-+60+=+0+
By looking at this I can see:
+%28+x+%2B+12+%29%2A%28+x+-+5+%29+=+0+
+x+=+5+ ( can't use the negative solution )
and
+x+%2B+7+=+12+
---------------------
The width is 5 ft
The length is 12 ft
------------------
check:
+5%5E2+%2B+12%5E2+=+13%5E2+
+25+%2B+144+=+169+
+169+=+169+
OK