Thursday, 3 July 2014

trigonometry - Find t for $Asin(w_1t) = -Bsin(w_2t)$

I am trying to solve t for the next equation:



$$A\sin(\omega_{1}t)+B\sin(\omega_{2}t)=0$$




Where:



$A > B$



$\omega_{1}$ AND $\omega_{2}$ are constants



Reading in wikipedia about trigonometric identities and following this post: Identity for a weighted sum of sines / sines with different amplitudes



I tried:




$$A\sin(\omega_{1}t)+B\sin(\omega_{2}t)=C\sin(\omega_{1}t+\varkappa)=0$$



Where:



$$C^2=A^2+B^2+2AB\cos(\omega_{2}t-\omega_{1}t)$$



And



$$\varkappa=\arcsin\frac{B\sin(\omega_{2}t-\omega_{1}t)}{C}$$




if $C\sin(\omega_{1}t+\varkappa)=0$, means that $C$ and/or $sin(\omega_{1}t+\varkappa)$ are equal to $0$, so I can get a partial solution by making $C=0$:



$$t=\frac{\arccos-\frac{A^2+B^2}{2AB}}{\omega_{2}-\omega_{1}}$$



But for the expression $sin(\omega_{1}t+\varkappa)=0$ I have not been able to solve it.



Someone can help me with this please?



Thanks

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