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# Help with trigonometric identities watch

1. I need help with this question, my maths teacher didn't help me at all (he kept saying "you should kmow how to do this!!") and he's expecting me to bring it in tomorrow

Here's the question:

Prove 1/cos(x) - cos(x) is identical to sin(x)tan(x)

And you can only use the identities:

cos^2(x) - sin^2(x) = 1
tan(x) = sin(x)/cos(x)

I'll try doing it while this gets approved so I hope it doesn't take long
2. I'm in year 10 btw and I think he said this is a level stuff so don't blame me if it's really easy
3. (Original post by turna127)
I need help with this question, my maths teacher didn't help me at all (he kept saying "you should kmow how to do this!!" and he's expecting me to bring it in tomorrow

Here's the question:

Prove 1/cos(x) - cos(x) is identical to sin(x)tan(x)

And you can only use the identities:

cos^2(x) - sin^2(x) = 1
tan(x) = sin(x)/cos(x)

I'll try doing it while this gets approved so I hope it doesn't take long
Actually, the identity is

Begin by writing as a single fraction.

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Updated: February 6, 2018
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