Answer
a) $\sqrt 2a$
b) The hypotenuse is the length of its leg multiplied by $\sqrt 2$.
Work Step by Step
a) We use the Pythagorean theorem to calculate the hypotenuse $h$ of the given right triangle:
$$\begin{align*}
h^2&=a^2+a^2\\
h^2&=2a^2\\
h&=\sqrt 2a.
\end{align*}$$
b) The length of the hypotenuse of a right isosceles triangle equals its length of a leg multiplied by $\sqrt 2$.
