H = 2sqrt2
D = 6sqrt3
In a 45,45,90 triangle the hypotenuse is (x)sqrt2 while the side lengths are equivalent being a single value x. Therefore, when given the hypotenuse and solving for the leg, divide 4 by sqrt2 to get 4sqrt2/2 which simplifies to 2sqrt2 when the denominator and numerator cancel.
In a 30,60,90 triangle the short leg x is across from the 30 degree angle meaning the angle across from the 60 degree angle is x times the sqrt of 3. Therefore the long leg is 6sqrt3
