Решите одну хотябы задачуууу

Решите задачу:

$2705)\quad \ \textless \ C=90^\circ \; ,\; \; tgA= \frac{2\sqrt{21}}{21} \; ,\; \; BC=6\; ,\; \; AB=?\\\\tgA= \frac{BC}{AC} = \frac{2\sqrt{21}}{21} \; \; \to \; \; AC= \frac{21 \cdot BC}{2\sqrt{21}} = \frac{21\cdot 6}{2\sqrt{21}} =3\sqrt{21}\\\\AB=\sqrt{AC^2+BC^2}=\sqrt{9\cdot 21+36}=\sqrt{225}=15\\\\\\2712)\quad \ \textless \ C=90^\circ \; ,\; \; cosA=\frac{3}{5}\; ,\; \; AB=25\; ,\; \; AH=?\\\\cosA= \frac{AC}{AB}= \frac{3}{5} \; \; \to\; \; AC= \frac{3\cdot AB}{5}=\frac{3\cdot 25}{5} =15$

$AC^2=AH\cdot AB\; \; \to \; \; AH=\frac{AC^2}{A}=\frac{15^2}{25}=9$