Answer: A
Explanation:
Use formula a^2 + b^2 = c^2 but in this case letter “d” will substitute for “b”
Since 13 is hypotenuse, 13 is going to be the letter c
12 is “a” because we don’t know “d”
So it’s 12^2 + d^2 = 13^2
Simplify: 144 + d^2 = 169
Subtract to isolate d^2: d^2 = 25
Take square root from both sides to isolate d: d = 5
Answer: A