what is the value of a?

Answer:
9\sqrt{2}
Step-by-step explanation:
this is a 30-60-90 triangle so
the side opposite of 30 is x and the opposite side of 60 is x[tex]\sqrt{2}[/tex]. then the side opposite 90 is 2x.
so if 9=x then a=x\sqrt{2}
9\sqrt{2} is the side length of a
Hope that helps :)