Algebraic refresh help needed...
The x-intercepts of y= -1/2 cos (x/2), are,
pi/2 & 3pi/2, but "HOW" algebraically do I find these points?.... I know you set y=0 and so cos of 0 is 1 which is pi/2, but I don't know how "algebraically" to find 3pi/2?... I know this is a simple explanation but im stuck

Question

Algebraic refresh help needed...
The x-intercepts of y= -1/2 cos (x/2), are,
pi/2 & 3pi/2, but "HOW" algebraically do I find these points?.... I know you set y=0 and so cos of 0 is 1 which is pi/2, but I don't know how "algebraically" to find 3pi/2?... I know this is a simple explanation but im stuck

anonymous · Answer

thank you anyways

anonymous · Answer

So the problem is...
$$y =\frac{ -1 }{ 2 } \cos \frac{ X }{ 2 }$$
and the x-intercepts are
$$\frac{ 3\Pi }{ 2 }\ and  \frac{ \Pi }{ 2 }$$
You can try working backwards. I'm not sure this is how your teacher wants it but this is how I worked it out. Instead of putting Y as 0, set X equal to its intercept.
I wrote this on a sticky note so excuse the lame picture, I didn't want to re-write everything on here. (SORRY FOR HOW LONG THIS TOOK!)

anonymous · Answer

thanks

anonymous · Answer

You're welcome and good luck! I'm working through trigonometry right now and all these sines and cosines and tangents and their inverses are getting all muddled up in my head! :p

anonymous · Answer

I have a similar question thats y= -2 cos x/4 , and i know to find the period it's 2pi/b but in this case is it, 2pi/4 or 2pi/1? i thought it was 2pi/1?