三角関数と双曲線関数の積分
三角関数の積分
(1)
\[ \int f(\sin x)\cos xdx=\int f(t)dt\cnd{t=\sin x} \](2)
\[ \int f(\cos x)\sin xdx=-\int f(t)dt\cnd{t=\cos x} \](3)
\[ \int f(\tan x)\frac{1}{\cos^{2}x}dx=\int f(t)dt\cnd{t=\tan x} \](4)
\[ \int f(\cos x,\sin x)dx=\int f\left(\frac{1-t^{2}}{1+t^{2}},\frac{2t}{1+t^{2}}\right)\frac{2}{1+t^{2}}dt\cnd{t=\tan\frac{x}{2}} \](1)
\begin{align*} \int f(\sin x)\cos xdx & =\int f(\sin x)d\left(\sin x\right)\\ & =\int f(t)dt\cnd{t=\sin x} \end{align*}(2)
\begin{align*} \int f(\cos x)\sin xdx & =-\int f(\cos x)d\left(\cos x\right)\\ & =-\int f(t)dt\cnd{t=\cos x} \end{align*}(3)
\begin{align*} \int f(\tan x)\frac{1}{\cos^{2}x}dx & =\int f(\tan x)d\left(\tan x\right)\\ & =\int f(t)dt\cnd{t=\tan x} \end{align*}(4)
\begin{align*} \int f(\cos x,\sin x)dx & =\int f\left(\cos^{2}\left(\frac{x}{2}\right)-\sin^{2}\left(\frac{x}{2}\right),2\sin x\cos x\right)dx\\ & =\int f\left(\frac{1-\tan^{2}\frac{x}{2}}{1+\tan^{2}\frac{x}{2}},\frac{2\tan\frac{x}{2}}{1+\tan^{2}\frac{x}{2}}\right)dx\\ & =\int f\left(\frac{1-t^{2}}{1+t^{2}},\frac{2t}{1+t^{2}}\right)d\left(2\tan^{\bullet}t\right)\cnd{t=\tan\frac{x}{2}}\\ & =\int f\left(\frac{1-t^{2}}{1+t^{2}},\frac{2t}{1+t^{2}}\right)\frac{2}{1+t^{2}}dt \end{align*}双曲線関数の積分
(1)
\[ \int f(\sinh x)\cosh xdx=\int f(t)dt\cnd{t=\sinh x} \](2)
\[ \int f(\cosh x)\sinh xdx=\int f(t)dt\cnd{t=\cosh x} \](3)
\[ \int f(\tanh x)\frac{1}{\cosh^{2}x}dx=\int f(t)dt\cnd{t=\tanh x} \](4)
\[ \int f(\cosh x,\sinh x)dx==\int f\left(\frac{1+t^{2}}{1-t^{2}},\frac{2t}{1-t^{2}}\right)\frac{2}{1-t^{2}}dt\cnd{t=\tanh\frac{x}{2}} \](1)
\begin{align*} \int f(\sinh x)\cosh xdx & =\int f(\sinh x)d\left(\sinh x\right)\\ & =\int f(t)dt\cnd{t=\sinh x} \end{align*}(2)
\begin{align*} \int f(\cosh)\sinh xdx & =\int f(\cosh x)d\left(\cosh x\right)\\ & =\int f(t)dt\cnd{t=\cosh x} \end{align*}(3)
\begin{align*} \int f(\tanh x)\frac{1}{\cosh^{2}x}dx & =\int f(\tanh x)d\left(\tanh x\right)\\ & =\int f(t)dt\cnd{t=\tanh x} \end{align*}(4)
\begin{align*} \int f(\cosh x,\sinh x)dx & =\int f\left(\cosh^{2}\left(\frac{x}{2}\right)+\sinh^{2}\left(\frac{x}{2}\right),2\sinh x\cosh x\right)dx\\ & =\int f\left(\frac{1+\tanh^{2}\frac{x}{2}}{1-\tanh^{2}\frac{x}{2}},\frac{2\tanh\frac{x}{2}}{1-\tanh^{2}\frac{x}{2}}\right)dx\\ & =\int f\left(\frac{1+t^{2}}{1-t^{2}},\frac{2t}{1-t^{2}}\right)d\left(2\tanh^{\bullet}t\right)\cnd{t=\tanh\frac{x}{2}}\\ & =\int f\left(\frac{1+t^{2}}{1-t^{2}},\frac{2t}{1-t^{2}}\right)\frac{2}{1-t^{2}}dt \end{align*}
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三角関数の積
\[
\prod_{k=1}^{n-1}\sin\frac{k\pi}{n}=\frac{n}{2^{n-1}}
\]
三角関数(双曲線関数)の逆三角関数(逆双曲線関数)が恒等写像になる条件
\[
\sin^{\bullet}\sin z=?z
\]
逆三角関数と逆双曲線関数の対数表示
\[
\Sin^{\bullet}z=-i\Log\left(iz+\sqrt{1-z^{2}}\right)
\]
三角関数と双曲線関数のn乗積分
\[
\int\sin^{2n+m_{\pm}}xdx=\frac{\Gamma\left(n+\frac{1}{2}+\frac{m_{\pm}}{2}\right)}{\Gamma\left(n+1+\frac{m_{\pm}}{2}\right)}\left\{ -\frac{1}{2}\sum_{k=0}^{n-1}\left(\frac{\Gamma\left(k+1+\frac{m_{\pm}}{2}\right)}{\Gamma\left(k+\frac{3}{2}+\frac{m_{\pm}}{2}\right)}\cos x\sin^{2k+1+m_{\pm}}x\right)+\frac{\Gamma\left(1+\frac{m_{\pm}}{2}\right)}{\Gamma\left(\frac{1}{2}+\frac{m_{\pm}}{2}\right)}\int\sin^{m_{\pm}}xdx\right\}
\]