Question 190849
20^2+x^2=(2x)^2
400+x^2=4x^2
x^2-4x^2=-400
-3x^2=-400
x^2=-400/-3
x^2=133.3
x=sqrt133.3
x=11.547 ans.
Proof:
20^2+11.547^2=(2*11.547)^2
400+133.3=23.094^2
533.3=533.3