Use the Pythagorean theorem

to find the missing side length of a right triangle
In this case, after you plug in the given numbers your equation is

Then, Just solve that equation for y.



y = 16
So the answer is B, 16 cm.
I hope this helps, please feel free to ask questions if you're still confused :)
Are you trying to find the area?
There are 15 boys what are you asking the sentence is not complete