\[\boxed{\mathbf{Страница}\mathbf{\ 41}\mathbf{.}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\boxed{\mathbf{142}\mathbf{.}\mathbf{\ }}\]
\[Общая\ часть:треугольник\ \]
\[\mathrm{\Delta}\text{KOC.}\]
\[\boxed{\mathbf{143}\mathbf{.}\mathbf{\ }}\]
\[(12 \cdot 8) \cdot 7 = 12 \cdot (8 \cdot 7)\]
\[(25 \cdot 4) \cdot 2 = 25 \cdot (4 \cdot 2)\]
\[(3 \cdot 9) \cdot 6 = 3 \cdot (9 \cdot 6)\]
\[(10 \cdot 4) \cdot 5 = 10 \cdot (4 \cdot 5)\]
\[\boxed{\mathbf{144}\mathbf{.}}\]
\[4 \cdot 2 \cdot 3 = 24 \Leftrightarrow 4 \cdot 6 = 24\]
\[4 + 2 + 3 = 9 \Leftrightarrow 4 + 5 = 9\]
\[1 \cdot 4 \cdot 2 = 8 \Leftrightarrow 1 \cdot 8 = 8\]
\[1 + 4 + 2 = 7 \Leftrightarrow 1 + 6 = 7\]