Hi all,

I am stuck on proving these two problems:

(csc theta - sin theta)^2 = cot^2theta - cos^2theta

and

(1+cos2theta/cos^2theta)=2

I know I need to use double angle identities in the second one, but I have been stuck on how to get going.

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- March 31st 2010, 07:54 PMBikkstahTrigonometric identity help
Hi all,

I am stuck on proving these two problems:

(csc theta - sin theta)^2 = cot^2theta - cos^2theta

and

(1+cos2theta/cos^2theta)=2

I know I need to use double angle identities in the second one, but I have been stuck on how to get going. - March 31st 2010, 07:58 PMProve It
- April 1st 2010, 12:57 PMBikkstah
Can anyone help with (1 + Cos2theta/cos^2theta)=2? I know it's true by setting theta equal to a real angle like 30 degrees, but I don't know how to prove it using just identities.

- April 1st 2010, 01:03 PMe^(i*pi)
- April 1st 2010, 02:35 PMBikkstah
Thank you both so much!