Answer :

TSO
For it to be a right angle triangle, use the phytagorean theorem [tex]a^2+b^2=c^2[/tex] to test it out.

[tex]15^2+36^2=39^2[/tex]
[tex]225+ 1296 = 1521[/tex]
[tex]1521 = 1521[/tex]

Since it equals, 15, 36, 39 is a right angle triangle!