Explanation:
there is something severely wrong with the problem definition.
when the Hypotenuse = 9, there is no 30-60-90 triangle with a leg = 6.
and when we are just focusing that this is a right-angled triangle with the Hypotenuse = 9, then 6 cannot be the longer leg.
it is also not clear what the solution is supposed to be. the 2nd leg ? the area ? the perimeter ? the height(s) ? ...
what ?
so, all I can do here is to show you why I said what I said :
30-60-90 triangle with Hypotenuse = 9
then the longer leg is opposite of the 60° angle and therefore sin(60)×9 = 7.794228634...
the shorter leg is opposite of the 30° angle and therefore sin(30)×9 = 0.5×9 = 4.5
a right-angled triangle with Hypotenuse = 9, one leg = 6 gives us per Pythagoras for the other leg
9² = 6² + leg²
81 = 36 + leg²
45 = leg²
leg = sqrt(45) = 6.708203932...
so, you see, as stated above, there is no leg with the length 6 in such a 30-60-90 triangle.
and in a more general right-angled triangle, if one leg = 6, then the other leg is actually longer.
therefore, there is everything wrong with the problem definition.