Question

What is the equation to solve this problem?

Answer 1

 

$\displaystyle\bf\\x^2+x^2=10^2\\\\2x^2=19^2\\\\x^2=\frac{10^2}{2}\\\\ \sqrt{x^2}=\sqrt{\frac{10^2}{2}}\\\\x=\frac{10\sqrt{2}}{\sqrt{2}\times\sqrt{2}}\\\\x=\frac{10\sqrt{2}}{2}\\\\\boxed{\bf x=5\sqrt{2}~~~~~~Correct~ansver:~~D)}$