Tolong dibantu dengan caranya...

[tex] {x}^{2} + {x}^{2} = {20}^{2} \\ 2 {x}^{2} = 400 \\ {x}^{2} = \frac{400}{2} = 200 \\ x = \sqrt{200} = 10 \sqrt{2} \: cm[/tex]