## exact value of sin(5pi/6-2pi)?

Trigonometric ratios and functions, the unit circle, inverse trig functions, identities, trig graphs, etc.
sully039
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Joined: Mon Jul 25, 2011 8:33 pm
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### exact value of sin(5pi/6-2pi)?

I'm not sure if I'm suppossed to find the value of 5pi/6 (which is 1/2) and then subtract 2pi from it. Or is it sin(5pi/6)-sin(2pi)?

Also, can anyone tell me how to figure out the equation of this tangent? I think the answer is tan(x-pi/4)-1, but I'm not sure. Graph is in link below.
http://imageshack.us/photo/my-images/14/graphkh.jpg

thanks

maggiemagnet
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Joined: Mon Dec 08, 2008 12:32 am
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### Re: exact value of sin(5pi/6-2pi)?

I'm not sure if I'm suppossed to find the value of 5pi/6 (which is 1/2) and then subtract 2pi from it. Or is it sin(5pi/6)-sin(2pi)?
Wow! They were supposed to teach you about functions before diving so deep into trig! To get up to speed, try a lesson on functions and another on function notation. Specifically, you'll see that the parentheses in function notation is not the same as parentheses for multiplication! In this case, you have the function, sine, being taken of the simplified value of -pi/6.
Also, can anyone tell me how to figure out the equation of this tangent? I think the answer is tan(x-pi/4)-1, but I'm not sure. Graph is in link below.
http://imageshack.us/photo/my-images/14/graphkh.jpg
Since the graph is already flexed back downward (in other words, it's not in the middle of its flexing) at (0, -1), then the function isn't going to be tan(something) - 1. It looks to me like you have a phase shift going on, but that's about all.

In f(x) = tan(x), what is the value of tan(-pi/4)? How can you relate that to the graph?