Posted by **Britt** on Tuesday, December 20, 2011 at 8:40pm.

{1/(sec x - 1)} - {1/(sec x +1)} = 2 cot^2 x

solve using identities?

- trigonometry -
**Damon**, Tuesday, December 20, 2011 at 8:41pm
Hey, I did this for you long ago.

- trigonometry -
**Damon**, Tuesday, December 20, 2011 at 8:41pm
Twice in fact

- trigonometry -
**Damon**, Tuesday, December 20, 2011 at 8:42pm
copy again

sin a cos b + cos a sin b = sin (a+b)

so sin (7t)

1/(1/cos x -1) - 1/(cos x +1)

cos x/(1 - cos x) - cos x/(1+cos x)

[cos x(1+cos x) - cos x(1-cos x)]/(1-cos^2 x)

[ cos x + cos^2x - cos x +cos^2 x]/sin^2x

2 cos^2 x/sin^2 x

2 cot^2 x

- trigonometry -
**Britt**, Tuesday, December 20, 2011 at 8:43pm
ohh, i didnt realize! thankyou :)

- trigonometry -
**Damon**, Tuesday, December 20, 2011 at 8:44pm
Please check before repeating posts. Some other teacher might have done it all over again.

- trigonometry -
**Britt**, Tuesday, December 20, 2011 at 8:56pm
okay!

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