diagonal = 9√2 ≈ 12.73
the diagonal splits the square into 2 right triangles with the hypotenuse being the diagonal of the square
using Pythagoras' identity
d = √(9² + 9²) = √162 = 9√2 ≈ 12.73 ( to 2 dec. places )
Answer:
If you have written the sides of both triangles in the same order , The congruent side will be ED . Else it could be anything . It would be more better if you could put a figure
Apologies if the diagram is a bit confusing
