omg I do not understand this

Answer:
missing length is 8
Step-by-step explanation:
17^2 - 15^2 = 64
square root of 64 is 8
Answer:
8 inches
Step-by-step explanation:
Use the Pythagorean Theorem:
a²+b²=c²
15²+b²=17²
225+b²=289
b²=64
b=8
Therefore, the missing side is 8 inches long.