Can someone please direct me in the correct identities to use here, really stuck!

given that 5sec^2x + 3tan^2x =9, find the possible values of sin x.

Thanks!

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- Dec 11th 2012, 12:36 PMDonGorgonC3 identity issue!
Can someone please direct me in the correct identities to use here, really stuck!

given that 5sec^2x + 3tan^2x =9, find the possible values of sin x.

Thanks! - Dec 11th 2012, 01:07 PMMarkFLRe: C3 identity issue!
Multiply through by $\displaystyle \cos^2(x)$ then apply the Pythagorean identity to get a quadratic in $\displaystyle \sin^2(x)$.

- Dec 11th 2012, 01:12 PMOllieCRe: C3 identity issue!
Knowing that: tan^2x + 1 = sec^2x, sec^2x = 1/cos^2x and also sin^2x + cos^2x = 1, is what is required to answer this question.

More specifically begin by getting everything in terms of sin x and cos x and hopefully it will become much easier to manipulate. - Dec 24th 2012, 01:52 AMibduttRe: C3 identity issue!