Question 982524
Change the whole description and question to this:

--
A triangle with 3 sides, AND one right angle.  The height is 5km and the HYPOTENUSE of the triangle is 13km.... The base is X..... What is the <s>volume</s> AREA of the TRIANGLE,  
in  km squared, THE BASE, X, and the perimeter?
--


Pythagorean Theorem formula will let you find the base.
{{{X^2+5^2=13^3}}}
{{{X^2=169-25}}}
{{{X^2=144}}}
{{{highlight(X=12)}}}--------Size of the base, kilometers.


Finding the area:
{{{(1/2)X*h}}}, if h is for "height".
{{{(1/2)12*5}}}, because you found X and were given height;
{{{6*5}}}
{{{highlight(30*squareKilometers)}}}


Find Perimeter:
Sum of the measures of the sides,
{{{X+h+slant}}}------you called the hypotenuse, "slant".
{{{12+5+13}}}
{{{highlight(30)}}}