To find any hypotenuse use the Pythagorean theorem:
First, square 36 (which would be 36 x 36) and square 64 (64 x 64).
Add them together.
Find the square root of the total.
That's your answer :)
Or you can just run it through this: https://www.google.com/search?q=how+to+calculate+hypotenuse&oq=how+to+calculate+hypot&aqs=chrome.0.0j69i57j0l6.8070j0j7&sourceid=chrome&ie=UTF-8