Answer: 15
Explanation:
For this you will have to use pythagoras’ theorem.
The formula for the shorter side of this triangle is u²=c²-b² (or in this case u²=17²-8²).
17²=289
8²=64
The formula becomes u²=289-64 or u²=225
Then to find u on its own you have to square root 225.
The square root of 225 is 15.