[tex]Dane:\\p=8\cdot10^{5} \ Pa =8\cdot10^{5} \ \frac{N}{m^{2}}\\g = 10\frac{N}{kg}\\d = 1000\frac{kg}{m^{3}} = 10^{3} \ \frac{kg}{m^{3}}\\Szukane:\\h = ?\\\\p = d\cdot g\cdot h \ \ /:(d\cdot g)\\\\h = \frac{p}{d\cdot g}\\\\h = \frac{8\cdot10^{5} \ \frac{N}{m^{2}}}{10^{3} \ \frac{kg}{m^{3}}\cdot10\frac{N}{kg}}=8\cdot10 \ m\\\\\boxed{h = 80 \ m}[/tex]
Odp. Głębokość jeziora Hańcza h = 80 m.