Not sure if you wanted us to answer or not, but here goes!
Yes and no, depending on how you look at a pentagon.
-Traditional pentagon, then no.
It is impossible to make a conforming pentagon out of equilateral triangles at all, due to angles required to form the pentagon, the triangles would not be equilateral.
-Any 5 sided polygon, then yes.
If you put the two triangles together so that the points touch, and two of their sides make a straight line, you will get a 5 sided polygon.