can someone please explain to me how they got from $\displaystyle \frac{-1}{4i}(e^{-1}+e^1) $ to $\displaystyle \frac{i}{2}cosh(1) $ coz if i did it i got $\displaystyle -\frac{1}{2i} cosh (1) $ soo sorry im so lost
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Originally Posted by Dgphru can someone please explain to me how they got from $\displaystyle \frac{-1}{4i}(e^{-1}+e^1) $ to $\displaystyle \frac{i}{2}cosh(1) $ coz if i did it i got $\displaystyle -\frac{1}{2i} cosh (1) $ soo sorry im so lost It's the same thing! $\displaystyle -\frac{1}{2i} = -\frac{i}{2i^2} = - \frac{i}{2\cdot(-1)} = \frac{i}{2}$
hahah i can be so stupid ><
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