| Zeile 60: |
Zeile 60: |
| | 3. | | 3. |
| | <math> | | <math> |
| − | A = 2\pi r^2 + \frac{2000}{r} | + | \begin{eqnarray} |
| − | </math>
| + | A &= &2\pi r^2 + \frac{2000}{r} |
| − | | + | A' &= &4\pi r - \frac{2000}{r^2} |
| − | <math>
| + | 0& =& 4\pi r - \frac{2000}{r^2} |
| − | A´ = 4\pi r - \frac{2000}{r^2}
| + | &\rightarrow& r ≈ 5,419cm |
| − | </math>
| + | \end{eqnarray}</math> |
| − | | |
| − | <math>
| |
| − | 0 = 4\pi r - \frac{2000}{r^2} | |
| − | </math>
| |
| − | | |
| − | <math> \rightarrow r ≈ 5,419cm </math>
| |
| | | | |
| | <math> | | <math> |