In the figure, ABCD and DEFG are squares. AC:FD=7:5, find CE(English isn't my native language. Please correct me if I have any grammatical mistakes.)

The diagonal ratio is given AC:FD=7:5.
The length of AG is 3cm.
To find CE.
The diagonals ratio is same as the side of square ratio.
Reason-
The diagonals are the square root of 2 multiply by side.
[tex]D=\sqrt{2}S[/tex]D denotes the diagonal and S denote the side, of suare.
So, the ratio of diagonal is same as the ratio of sides of square.
[tex]\frac{D}{d}=\frac{S}{s}[/tex]Here D and d denotes the diagonal of the squares and s and S is the sides of squares.
Let AD = 7x , GD = 5x
[tex]\begin{gathered} AG=AD-GD \\ 3=7x-5x \\ 3=2x \\ x=1.5 \end{gathered}[/tex]Now find the length of CE,
[tex]\begin{gathered} CE=CD+DE \\ CE=7x+5x \\ CE=12x \end{gathered}[/tex]Substitute the value of x in the CE.
[tex]\begin{gathered} CE=12\times1.5 \\ CE=18cm \end{gathered}[/tex]Hence thelenghth CE is 18cm.