This isn't my problem, it's a friends. I'll post my explanation and you tell me what's wrong with it cause she still doesn't understand. Thanks.(adsbygoogle = window.adsbygoogle || []).push({});

[PLAIN][PLAIN]http://img43.imageshack.us/img43/3020/32112328.png [Broken] [Broken]

Find tan(theta), given the coordinates of the arrow.

I said

"well tanx = tan(x-180) by looking at the tan graph, which repeats every 180 So we can add 180 degrees to that angle, and take the tan of that instead"

(picture)

"the tan of that is op/adj which is easier

If the original vector was (a,b)

Then this vector is gonna be (-a,-b)"

(picture)

"tan of ( ) = tan of ( )

so if the first angle is -120, then the second is -120+180=60

and tan(-120) = tan(60)"

--------

This is the conversation if you're curious...sigh. Don't have to read this bit, but I would kind of like to know how to handle this situation.

B:so if it was like

[PLAIN][PLAIN]http://img43.imageshack.us/img43/3020/32112328.png [Broken] [Broken]

and it was like whats tan theta so do i just do tan of the small triangle thing then + pi/2?

A:well tanx = tan(x-180) by looking at the tan graph, which repeats every 180 So we can add 180 degrees to that angle, and take the tan of that instead

B:too confusing dont understand what youre saying

A:

[PLAIN][PLAIN]http://img168.imageshack.us/img168/2210/79577809.png [Broken] [Broken]

angle there is x+180

B:but its not asking for that angle

A:Tan (that angle) is tan(theta)

they are the same

B: so i was supposed to move the graph sideways or what?

A:Yeah

B:..?

http://img43.imageshack.us/img43/3898/11665177.png [Broken]

is not the same as

http://img43.imageshack.us/img43/1285/16166454.png [Broken]

A:the tangent of both angles are the same though

B:the angles are DIFFERENT

****

i dont know why i ask you

forget it

A:Yes, the angles are different, but tan(angle1) = tan(angle2)

B: obviously if you say it once and i dont get it

if you say the same thing again

i am still not gonna get it

(insert more irrelevant conversation)

A:The quickest explanation is that the tan graph repeats every 180, hence tan{x}=tan{x+180}

B:what does that have to do

WITH ANYTHING?????

A: it means if we want tan{x} (theta=x for now) but x is hard to deal with, we can add 180 as many times as we want, and take the tan{ } of that instead.

Bk

again im gonna ask you

what does that have to do with anything

ok if the component is (A,B) then what is the answer

A:[PLAIN][PLAIN]http://img168.imageshack.us/img168/2210/79577809.png [Broken] [Broken]

And the tan of that is op/adj which is easier

If the original vector was (a,b)

Then this vector is gonna be (-a,-b)

so b/a

B: ok so basically what i got out of what you said is

http://img168.imageshack.us/img168/5272/12495044.png [Broken]

which i already know is wrong so thanks anyway

A:tan of ( ) = tan of ( )

so if the first angle is -120, then the second is -120+180=60

and tan(-120) = tan(60)

The rest is more swearing than explanation so I won't paste it in.

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# Tan of ugly (negative angle)

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