Help with Trig Function: Sec(2x)csc(x)sin(2x) and C=cosx

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Homework Help Overview

The discussion revolves around rewriting the expression sec(2x)csc(x)sin(2x) in terms of C, where C is defined as cos(x). Participants are exploring trigonometric identities and simplifications to express the function solely in terms of C.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants attempt to manipulate the expression using trigonometric identities, questioning how to eliminate sin(x) in favor of cos(x). There are discussions about simplifying the expression and substituting C for cos(x) at various stages.

Discussion Status

Some participants have provided guidance on how to proceed with the simplification and substitution process. There is an ongoing exploration of different forms of the expression, and while some participants express confidence in their results, there is no explicit consensus on the final answer.

Contextual Notes

Participants are working under the assumption that they must express everything in terms of C, and there are indications of potential errors in calculations that are being addressed throughout the discussion.

Mark53
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Homework Statement


Let C=cosx. Write sec(2x)csc(x)sin(2x) as a function of C.

The Attempt at a Solution



Am I on the right track

1/cos(2x) * 1/sin(x) * 2sin(x)cos(x)

1/(cos^2(x)-sin^2(x)) * `1/(sqrt(1-cos^2(x)) * 2(sqrt(1-cos^2(x))cos(x)

What would i do from here?
 
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There is one ##\sin x## left in your formula that you need to convert to only using ##\cos x##.
Having done that, you only need to replace every ##\cos x## by ##C##, then simplify as much as possible.
 
Mark53 said:

Homework Statement


Let C=cosx. Write sec(2x)csc(x)sin(2x) as a function of C.

The Attempt at a Solution



Am I on the right track

1/cos(2x) * 1/sin(x) * 2sin(x)cos(x)

1/(cos^2(x)-sin^2(x)) * `1/(sqrt(1-cos^2(x)) * 2(sqrt(1-cos^2(x))cos(x)

What would i do from here?

So you got ##\frac{1}{\cos^2(x)-\sin^2(x)}\frac{1}{\sin(x)}2\sin(x)\cos(x)=\frac{2sin(x)\cos(x)}{(\cos^2(x)-\sin^2(x))\sin(x)}##

Why don't you simplify with sin(x)?
 
andrewkirk said:
There is one ##\sin x## left in your formula that you need to convert to only using ##\cos x##.
Having done that, you only need to replace every ##\cos x## by ##C##, then simplify as much as possible.

1/(cos^2(x)-sin^2(x)) * `1/(sqrt(1-cos^2(x)) * 2(sqrt(1-cos^2(x))cos(x)

1/(cos^2(x)-(1-cos^2(x) * 1/(sqrt(1-cos^2(x)) * 2(sqrt(1-cos^2(x))cos(x)

simplifying this I get

1/(cos(x)-1)

=1/(C-1)

Is this the correct answer?
 
Mark53 said:
1/(cos^2(x)-sin^2(x)) * `1/(sqrt(1-cos^2(x)) * 2(sqrt(1-cos^2(x))cos(x)

1/(cos^2(x)-(1-cos^2(x) * 1/(sqrt(1-cos^2(x)) * 2(sqrt(1-cos^2(x))cos(x)

simplifying this I get

1/(cos(x)-1)

=1/(C-1)

Is this the correct answer?

made a mistake it should be

2C/(2C^2-1)
 
Mark53 said:
made a mistake it should be

2C/(2C^2-1)
Finally, that is correct.
 
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