The applet below provides an introduction as to how we label the legs of a right triangle with respect to ONE of its acute angles. (Notice angle A, B, A', and B' are acute angles of a right triangle.)
The triangles shown below are similar triangles. Can you explain why?

1) How would you describe the hypotenuse of a right triangle? What is it? How do you easily find it?
2) How, within a right triangle, would you be able to identify an acute angle's OPPOSITE LEG?
3) How, within a right triangle, would you be able to identify an acute angle's ADJACENT LEG?