- #1

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## Homework Statement

seems simple, but i am stumped. Says write cos(x) in terms of tan(x).

## Homework Equations

would this be a reciprocal equation? or a Pythagorean? I'm lost

## The Attempt at a Solution

i dont even know where to begin.

- Thread starter 06Sport
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- #1

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seems simple, but i am stumped. Says write cos(x) in terms of tan(x).

would this be a reciprocal equation? or a Pythagorean? I'm lost

i dont even know where to begin.

- #2

mathwonk

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sin/cos = tan, so cos= sin/tan. har har.

can you use derivatives?

can you use derivatives?

- #3

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Edit: Beaten to it.

- #4

mathwonk

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DO YOU KNOW WHaT TAN' IS? or 1 + tan^2?

- #5

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sin/cos = tan, so cos= sin/tan - these are what i have. But would that be the answer? tan= sin/cos ? or cos=sin/tan?

- #6

mathwonk

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i was joking. read my second post.

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now im even more confused.

would it be cos=sin/tan?

would it be cos=sin/tan?

- #8

arildno

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How can you express sine in terms of cosine?

- #9

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i dont knowHow can you express sine in terms of cosine?

- #10

arildno

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Well, what RELATION exists between the sine and cosine of an angle?

- #11

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[itex]\sin x= \sqrt{1-cos^2x}[/itex]

Last edited:

- #12

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i need cos(theta) in terms of tan(theta) though. Unless thats what we are working up to :)

- #13

arildno

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So, look at the last identity you posted.

What do you get by dividing ôn both sides with cos^{2} ?

What do you get by dividing ôn both sides with cos^{2} ?

- #14

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sin^2 = 1/cos^2?

- #15

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[tex] sin^2 x + cos^2 x = 1[/tex]

look

http://en.wikipedia.org/wiki/List_of_trigonometric_identities

- #16

arildno

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Don't you know how to divide an equation with a number?sin^2 = 1/cos^2?

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- #19

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Only works for 1st and 2nd quadrant angles, that is, angles between 0 and 180 degrees. (or between 0 and 2Pi). Plus, it works for 0 degrees and 180 degrees. If you're in the 3rd or 4th quadrant, then you'd have to use a negative square root.[itex]\sin x= \sqrt{1-cos^2x}[/itex]

Last edited:

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yes,

how to use +- in latex?

how to use +- in latex?

- #21

cristo

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In latex the command for +/- is \pmhow to use +- in latex?

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