Answer
Length of side 1 $= 28$
Length of side 2 $= 56$
Length of side 3 $= 42$
Work Step by Step
Let $x$ be the shortest side.
Length of side 1 $= x$
Length of side 2 $= 2x$
Length of side 3 $= 14 + x$
$x+2x+14+x=126$
$4x+14=126$
$4x=112$
$x=28$
Length of side 1 $= x=28$
Length of side 2 $= 2x=2(28)=56$
Length of side 3 $= 14 + x=14+28=42$
