(dr(θ))/(r(θ))=(r(θ)dθ)/(θ^2)

解

\frac{d r ( θ )}{r ( θ )} = \frac{r ( θ ) d θ}{θ ^{2}}

θ = c_{1} r, θ = \frac{c _{1}}{r}

解答ステップ

\frac{d r}{r} = \frac{r d θ}{θ ^{2}}

θ

を従属変数にする。

d r

で割る:

\frac{\frac{d θ}{d r}}{r \frac{d θ}{d r}} = \frac{r \frac{d θ}{d r} \cdot \frac{d θ}{d r}}{θ ^{2}}

\frac{d θ}{d r}

を以下で代用:

θ^{'} (r)

\frac{θ ^{^{'}} ( r )}{r θ ^{^{'}} ( r )} = \frac{r θ ^{^{'}} ( r ) θ ^{^{'}} ( r )}{θ ^{2}}

分離する

θ^{'} (r) : θ^{'} (r) = \frac{θ}{r}, θ^{'} (r) = - \frac{θ}{r}

θ^{'} (r) = \frac{θ}{r} : θ = c_{1} r

θ^{'} (r) = - \frac{θ}{r} : θ = \frac{c _{1}}{r}

θ = c_{1} r, θ = \frac{c _{1}}{r}