Use Pythagorean theorem

15

Step-by-step explanation:

a^2+b^2=c^2

y^2+8^2=17^2

Step 1: Simplify both sides of the equation.

y^2+64=289

Step 2: Subtract 64 from both sides.

y^2+64−64=289−64

y^2=225

Step 3: Take square root.  

y=15  

answer: 38.47 is your answer

step-by-step explanation: hope i you and who ever sees this answer have a great rest of your day : )