for 0<=θ<=360, solve (sinθ+1)(2cosθ-1)=0

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- Aug 26th 2009, 10:25 PMdeej813yr11 2U trig
for 0<=

**θ**<=360, solve (sin**θ**+1)(2cos**θ**-1)=0 - Aug 26th 2009, 10:35 PMChris L T521
- Aug 26th 2009, 10:50 PMdeej813
do i just put sin^-1(-1) in my calculator

and cos^-1(1/2)

??

sorry im very confused - Aug 26th 2009, 11:09 PMChris L T521
You could...but its best if you try to memorize these values from the unit circle: Unit circle - Wikipedia, the free encyclopedia

In our case, $\displaystyle \sin^{-1}\left(-1\right)$ has only one value in the specified interval for $\displaystyle \theta$, and its $\displaystyle \theta=270^{\circ}$

However, $\displaystyle \cos^{-1}\left(\tfrac{1}{2}\right)$ has two solutions in the given interval for $\displaystyle \theta$. They are $\displaystyle \theta_1=60^{\circ}$ and $\displaystyle \theta_2=300^{\circ}$.

Your final answer to the original question is all three values for $\displaystyle \theta$.

Does this make sense? - Aug 26th 2009, 11:15 PMdeej813
yes i get it

finally :)

thanks