Please help if you are fluent with the terms cos, etc. When you get your answer could you please explain to me how you got it? It would mean so much. Thank you, in advance.

Question

Please help if you are fluent with the terms cos, etc.  When you get your answer could you please explain to me how you got it?  It would mean so much.  Thank you, in advance.

anonymous · Answer

Here's the equation.
$$4 \cos \theta = 3 \cos \theta -\sqrt{3/2}  for  0 \le \theta <2$$

anonymous · Answer

And here are my possible answers.
A. $$5\pi/6,   7\pi/6$$
B. $$\pi/6,   11\pi/6$$
C. $$\pi/3,  5\pi/3$$
D. none of these.

kc_kennylau · Answer

Take 3cos(theta) from both sides :)

kc_kennylau · Answer

(take=subtract)

anonymous · Answer

Alright, so factor them out.  :)

kc_kennylau · Answer

not factor :p

anonymous · Answer

in what quadrants is cosine a negative value?

kc_kennylau · Answer

$$\begin{array}{rcl}
4\cos\theta&=&3\cos\theta-\frac{\sqrt3}2\
4\cos\theta-3\cos\theta&=&-\frac{\sqrt3}2\
\cos\theta&=&-\frac{\sqrt3}2
\end{array}$$

anonymous · Answer

@kc_kennylau yes, I understand that.

anonymous · Answer

Thank you :) what happens next?

anonymous · Answer

In which quadrants is cosine negative?
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