Since it is a right triangle, we can apply the Pythagorean theorem:
c^2 = a^2 + b^2
where:
c = hypotenuse = 16
a &b = the other 2 legs of the triangle (11 and x )
Replacing:
16^2 = 11^2 + x^2
Solve for x:
256 = 121 + x^2
256-121 = x^2
135 = x^2
√135 = x
11.6 = x
x = 11.6 m