Question 1209970
<pre>
{{{drawing(400,2400/13,-13, 13,-6,6,

locate(-2.2,2.5,matrix(1,2,5,cm)),
locate(5.1,3.7,matrix(1,2,13,cm)),
line(-12,0,0,5),
line(0,5,12,0),
line(12,0,0,-5),
line(0,-5,-12,0),
line(-12,0,12,0),
line(0,-5,0,5)  )}}}

This is a rhombus is made of 4 special right triangles. 
These are 5-12-13 right triangles.

Each of them has shorter leg = 5, hypotenuse = 13, and therefore
longer leg = {{{sqrt(13^2-5^2)=sqrt(169-25)=sqrt(144)=12}}}

So each 5-12-13 right triangle below has base = 12 and height = 5

So each of the four 5-12-13 right triangles has area

{{{A=expr(1/2)*base*height=expr(1/2)*12*5=matrix(1,2,30,cm^2)}}} 
 
and since there are 4 of them, the total area = {{{4*30 = 120}}} cm<sup>2</sup>.

I think you are studying special right triangles, so this is a good
page to look at:

https://flexbooks.ck12.org/cbook/ck-12-precalculus-concepts-2.0/section/4.3/primary/lesson/special-right-triangles-pcalc/

Edwin</pre>