a = 3
h = 2
[tex]P = a\cdot h\\oraz\\P = a^{2}\sin\alpha}\\\\a^{2} sin\alpha = ah \ \ /:a^{2}\\\\sin \alpha = \frac{ah}{a^{2}} = \frac{h}{a}\\\\\boxed{sin\alpha = \frac{2}{3}}[/tex]
