Question 38581
{{{A = (1/2)*b*h}}}

{{{200 = (1/2)*10*h}}}
{{{200 = 5h}}}
{{{40 = h}}}


The isosceles triangle is actually TWO right triangles, where the base of the isosceles triangle is split in half.  Therefore the base of the right triangle is 5 units, and the height is 40 units.  Let c = the length of the hypotenuse of the right triangle, which is also one of the equal sides of the isosceles triangles.


{{{a^2 + b^2 = c^2}}}
{{{5^2 + 40^2 = c^2}}}
{{{25 + 1600 = c^2}}}
{{{1625 = c^2}}}

{{{c= sqrt(1625)= sqrt(25)*sqrt(65)}}}
{{{c = 5*sqrt(65)}}}


Perimeter = sum of the THREE external sides, where 
Base = 10 units
Each equal side = {{{5*sqrt(65) }}}


Perimter = Base + 2 equal sides
{{{ P = 10 + 2*5*sqrt(65) }}}
{{{ P = 10 + 10*sqrt(65) }}}

R^2 at SCC