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IrinaK [193]
3 years ago
6

Trigonometric Identities and Applications? help

Mathematics
1 answer:
Vadim26 [7]3 years ago
3 0
\bf h=-15cos\left( \frac{2\pi }{5}t \right)\qquad \boxed{h=8}\qquad 8=-15cos\left( \frac{2\pi }{5}t \right)
\\\\\\
\cfrac{8}{-15}=cos\left( \frac{2\pi }{5}t \right)\implies cos^{-1}\left(  \frac{8}{-15}\right)=cos^{-1}\left[ cos\left( \frac{2\pi }{5}t \right) \right]
\\\\\\
cos^{-1}\left(  \frac{8}{-15}\right)=\cfrac{2\pi }{5}t\implies \cfrac{5}{2\pi }\cdot  cos^{-1}\left(  \frac{8}{-15}\right)=t\\\\
-------------------------------

\bf cos^{-1}\left(  \frac{8}{-15}\right)=\stackrel{radians}{\stackrel{II~quadrant}{\approx 2.13}~~,~~\stackrel{III~quadrant}{\approx 4.15}}\qquad \qquad 
t=
\begin{cases}
\frac{5}{2\pi }\cdot 2.13\\\\
\frac{5}{2\pi }\cdot 4.15
\end{cases}
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