Using Pythagorus Theorem:
a^2+b^2=c^2
So
20^2 + b^2 = 52^2
To find b^2:
52^2 - 20^2 = 2304
The square root of 2304 is 48
So to calculate how much smaller it is than a 48m pool you have to do 50-48 which equals 2
So the pool is 2m shorter than a 50m long pool.
:)
