\[Страница\ 39.\]
\[20.\ Формулы\]
\[\boxed{\mathbf{1}.}\]
\[Формула\] | \[a\] | \[b\] | \[c\] | \[S\] |
---|---|---|---|---|
\[S = ab + c\] | \[56\] | \[0\] | \[34\] | \[34\] |
\[S = a\ :b - c\] | \[96\] | \[3\] | \[19\] | \[13\] |
\[S = a + b + c\] | \[7\] | \[15\] | \[28\] | \[50\] |
\[S = a \cdot b \cdot c\] | \[7\] | \[5\] | \[3\] | \[105\] |
\[\boxed{\mathbf{2}.}\]
\[v,\ \frac{км}{ч}\] | \[65\] | \[17\] | \[6\] | \[12\] | \[21\] | \[18\] |
---|---|---|---|---|---|---|
\[t,\ ч\] | \[2\] | \[4\] | \[15\] | \[8\] | \[5\] | \[7\] |
\[s,\ км\] | \[130\] | \[68\] | \[90\] | \[96\] | \[105\] | \[126\] |
\[\boxed{\mathbf{3}.}\]
\[P = a + a + a = 3a.\]
\[\textbf{а)}\ a = 35\ см:\]
\[P = 35 \cdot 3 = 105\ см.\]
\[\textbf{б)}\ a = 28\ см:\]
\[P = 28 \cdot 3 = 84\ см.\]
\[\boxed{\mathbf{4}.}\]
\[P = 2a + 2b = 2 \cdot (a + b).\]
\[a = 160\ мм = 16\ см;\ \ b = 23\ см:\]
\[P = 2 \cdot (16 + 23) = 2 \cdot 39 =\]
\[= 78\ см.\]