Answer:

Step-by-step explanation:
Let's pretend the empty, white space in the middle is a triangle. A right triangle. then we just use the pythogerean theorem to get the a.

If it is a right triangle and AC is the hypotenuse, then AC is 5.
This is a Pythagorean Triple 3-4-5
Answer:
http://mansfieldalgebra1.weebly.com/uploads/1/0/4/4/10447339/rc_2_answer_key.pdf
Step-by-step explanation: