Question 900230
h for the altitude.
b for the base.  This one "one side of the triangle".
b=12+2h.
(1/2)b*h=27, using formula for area of a triangle.


{{{(1/2)(2h+12)h=27}}}
{{{(h+6)h=27}}}
{{{h^2+6h=27}}}
{{{h^2+6h-27=0}}}
{{{(h-3)(h+9)=0}}}
{{{highlight(h=3)}}}
-
{{{b=2h+12}}}
{{{b=2*3+12}}}
{{{b=6+12}}}
{{{highlight(b=18)}}}