Notice that the given right triangle has a marked angle measuring 45^(∘). Therefore, by the Triangle Angle Sum Theorem, the measure of the third angle must also be 45^(∘).
In a 45^(∘)-45^(∘)-90^(∘) triangle, the legs are congruent and the hypotenuse is sqrt(2) times the length of a leg. With this information, we can find the value of variable a.
9sqrt(2) = sqrt(2) * a
Finally, we can solve the above equation for a.
