Answer:
Answer: They are both right triangles so you can use the Pythagorean Theorem to get the length of the missing side
12^2 = 144. 5^2 = 25. 144 + 25 = 169. 13^2 = 169. Or you could say the sure root of 169 is 13.
Explanation:
The triangles are congruent because the three sides of triangle A are equal to the three sides of triangle B.
In geometry they call that proof "sss" meaning 3 same sides. Or you could prove by "sas" 2 equal sides and an equal angle.