Find the area and the angles formed by the diagonals of the rhombus given its height and the relationship between the height and the side length Find the area and the angles formed by the diagonals of the rhombus, if its height is two times smaller than the length of its side and is $4.2$.

My attempt

Let's write down the height:
$$h=\frac{a}{2}=4.2=\frac{21}{5}$$
From that we have
$$\frac{a}{2}=\frac{21}{5}\leftrightarrow5a=42\leftrightarrow a=\frac{42}{5}=8.4$$
Therefore, the area is
$$A=\frac{21}{5}\cdot\frac{42}{5}=\frac{882}{25}=35.28$$
I'm quite sure that I've got the area right. I need help with finding the angles. So... can someone help me find them?
hint: Area= Ht*width/2 ; diagonals cut orthogonally!
hint: Area= Ht*width/2 ; diagonals cut orthogonally!