Answer:
8.7m
Explanation:
Use the Pythagorean theorem, a^2 + b^2 = c^2
a and b are the sides going either horizontally or vertically, it doesn't matter which is which as long as it's only between those 2.
c is the diagonal side, also called the hypotenuse.
so plug in:
a^2 + b^2 = c^2
5^2 + b^2 = 10^2
25 + b^2 = 100
subtract 25 from both sides
b^2 = 75
square root both sides
b = 8.66, round it up and it's 8.7