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October 20, 2014

October 20, 2014

Posted by **Sara** on Wednesday, June 13, 2012 at 2:06am.

Thank you!

- Trig -
**Reiny**, Wednesday, June 13, 2012 at 7:58amIf csc Ø = 13/12, the sinØ = 12/13

so we are dealing with the 12-5-13 right-angled triangle in II

then cosØ = -5/13

sin 2Ø = 2sinØcosØ

= 2(12/13)(-5/13)

= -120/169

cos 2Ø = cos^2 Ø - sin^2 Ø

= 25/169 - 144/169

= -119/169

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