Please help: How to solve this problem using trig identities  TOPIC_SOLVED

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Please help: How to solve this problem using trig identities

Postby Skylar on Thu Feb 02, 2012 5:23 am

how can i simplify this equation using trig identities/formulas:

cosy = sqrt{sin4x + 4cos2x} - sqrt{cos4x + 4sin2x}
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Postby stapel_eliz on Thu Feb 02, 2012 11:19 am

Skylar wrote:cosy = sqrt{sin4x + 4cos2x} - sqrt{cos4x + 4sin2x}

What are you given as the relationship between "x" and "y"? Thank you! :wink:
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Re: Please help: How to solve this problem using trig identi

Postby Skylar on Thu Feb 02, 2012 3:00 pm

I think we are just supposed to simplify the expression on the right side of the equation. The instructions are to "express y in terms of x"
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Postby stapel_eliz on Thu Feb 02, 2012 6:03 pm

Skylar wrote:I think we are just supposed to simplify the expression on the right side of the equation. The instructions are to "express y in terms of x"

Then you're not supposed to simplify; you're supposed to solve for y.

A good start will be to apply the Pythagorean Identity to the quadric terms. For instance, restate (cos2(x))2 in terms of sine, and then combine with the other sine term inside that square root. And so forth.

Once you have the right-hand side simplified somewhat, you can take the inverse. :wink:
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