we where given two sides of the triangle without the third side
lets take the given sides to a and b
then let the third side be c which is also x
let a = 16
b = 10
c = x
using pythagoras theorem
x^2 = a^2 - b^2
x^2 = 16^2 - 10^2
x^2 = 256 - 100
x^2 = 156
therefore,
x = the square root of 156
x = 12