# Formulas of Trigonometric and Logarithmic Functions

1) $Sinx = \frac{{{e^{ix}} – {e^{ – ix}}}}{{2i}}$

2) $Cosx = \frac{{{e^{ix}} + {e^{ – ix}}}}{2}$

3) $Tanx = \frac{{{e^{ix}} – {e^{ – ix}}}}{{i({e^{ix}} + {e^{ – ix}})}}$

4) $Cotx = \frac{{i({e^{ix}} + {e^{ – ix}})}}{{{e^{ix}} – {e^{ – ix}}}}$

5) $Secx = \frac{2}{{{e^{ix}} + {e^{ – ix}}}}$

6) $Co\sec x = \frac{{2i}}{{{e^{ix}} – {e^{ – ix}}}}$

7) $Log(x + iy) = Log\sqrt {{x^2} + {y^2}} + iTa{n^{ – 1}}\left( {\frac{y}{x}} \right)$

8) $Log\left( {\frac{{x + iy}}{{x – iy}}} \right) = 2iTa{n^{ – 1}}\left( {\frac{y}{x}} \right)$