Question 1160966
<pre>
This is a trick question, because if the sides are in that ratio then the sum of
the two shorter sides would add up to equal to the longest sides and there could
be no such triangle.

But maybe the problem includes "degenerate triangles", triangles that contain 180°
angles and 0° angles, which degenerate into a line segment.  

Then 1:2:1 = 1k:2k:1k where the sides are 1k, 2k and 1k, then

Perimeter = 1k+2k+1k = 125
                  4k = 125
                   k = 31.25

The sides would be 31.25, 62.5 and 31.25  That would amount to a line segment
62.5 cm long.  So for the perimeter to be 125 cm, you would have to consider it
a double line segment, where one half of it coincides with the other half of it.

Heck, I'd just say "There is no such triangle", and forget "degenerate triangles".  

Edwin</pre>