(x + 10)² - 1
= (x² + 20x + 100) - 1
= x² + 20x + 99
None of the choices you provided are correct. Did you type in the question wrong?
I think you can draw two of them.
As you walk around the triangle in the clockwise direction,
you can run into the sides in the order of
3 ==> 4 ==> 1
or in the order of
3 ==> 1 ==> 4 .
Those are mirror images of each other. So they're not congruent,
and I think they're considered different triangles.
