5) ME=12, MF=16.

По теореме о секущихся: $$MH \cdot ME = MP \cdot MF$$ $$MH \cdot 12 = (12+x) \cdot 12 = 16 \cdot 16$$ $$12+x = \frac{16 \cdot 16}{12} = \frac{256}{12} = \frac{64}{3}$$ $$12 + x = \frac{64}{3}$$ $$x = \frac{64}{3} - 12 = \frac{64 - 36}{3} = \frac{28}{3} = 9 \frac{1}{3}$$ $$RH = \frac{28}{3}$$ Ответ: 9 1/3