cos2x + √3sin2x = 2 ????????????

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- Mar 18th 2013, 09:35 AMOmarAj96Real Hard Trigonometry Question ?
cos2x + √3sin2x = 2 ????????????

- Mar 18th 2013, 09:52 AMHallsofIvyRe: Real Hard Trigonometry Question ?

Let y= sin(2x).

Square both sides to get a quadratic equation for y. - Mar 18th 2013, 09:55 AMOmarAj96Re: Real Hard Trigonometry Question ?
Isn't cos2x = 1 - 2sin^2 x ?? So why apply the square root ?

And I think you meant =2 instead of +2 in the first line. - Mar 18th 2013, 10:06 AMOmarAj96Re: Real Hard Trigonometry Question ?
Isn't cos2x = 1 - 2sin^2 x ?? So why apply the square root ?

And I think you meant =2 instead of +2 in the first line. - Mar 18th 2013, 03:08 PMProve ItRe: Real Hard Trigonometry Question ?
Yes it is. But that's not what HallsOfIvy did. He applied the Pythagorean Identity. Notice how what he did is still in terms of sin(2x), not sin(x)?

- Mar 18th 2013, 05:12 PMSorobanRe: Real Hard Trigonometry Question ?
Hello, OmarAj96!

Quote:

Divide by 2: .

Then we have:

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