s = \frac{A_{2} B_{2}}{A_{1} B_{1}} = \frac{A B \cdot A_{2} O_{1}}{f} \cdot \frac{25}{A B \cdot A_{1} O_{1}} = \frac{25}{f} .

${s = \frac{A_2 B_2}{A_1 B_1} = \frac{A B \cdot A_2 O_1}{f} \cdot \frac{25}{A B \cdot A_1 O_1} = \frac{25}{f} .}$

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