Explanation:
Pythagoras
c² = a² + b²
c being the Hypotenuse (the side opposite of the 90° angle). a and b are the legs.
so, in our case,
27² = 16² + x²
729 = 256 + x²
473 = x²
x = sqrt(473)
473 = 11×43 and has therefore no squared factors.
therefore, it cannot be further simplified.