Let's begin by identifying key information given to us:
We have square ABCD
[tex]\begin{gathered} AE=3x+5 \\ BD=10x+2 \\ BD=2\cdot AE \\ 10x+2=2(3x+5) \\ 10x+2=6x+10 \\ \text{Put like terms together, we have:} \\ 10x-6x=10-2 \\ 4x=8 \\ \text{Divide both sides by ''4'', we have:} \\ \frac{4x}{4}=\frac{8}{4} \\ x=2 \\ \\ \end{gathered}[/tex]
For a square, the diagonals are equal, AC = BD
[tex]\begin{gathered} AC=BD \\ AC=10x+2 \\ x=2 \\ AC=10(2)+2=20+2 \\ AC=22 \end{gathered}[/tex]
