The triangle on the image is a right triangle which means we can use trigonometry to untangle its mysteries.
We have a side an and angle from that we can compute anything.
We will first compute x, we do so by taking the cosine of an angle,
![\cos(45)=(5√(2))/(x)](https://img.qammunity.org/2022/formulas/mathematics/college/am6s2mnqmbaaiwz4gk088lg61e2g9mxgb6.png)
![x=(5√(2))/(\cos(45))=(5√(2))/((√(2))/(2))=(10√(2))/(√(2))=\boxed{10}](https://img.qammunity.org/2022/formulas/mathematics/college/18a81c6len6pkymrjuu5lnblga9itr2mdb.png)
Then we can also compute y, simply by using pythagorean theorem,
![10^2=y^2+(5√(2))^2](https://img.qammunity.org/2022/formulas/mathematics/college/dzlmz29a5up1m3fqqadq7pivj37odoypnt.png)
.
So triangle has sides
which is also known as equilateral triangle.
Hope this helps :)