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September 19, 2014

September 19, 2014

Posted by **lindsay** on Thursday, May 9, 2013 at 1:21pm.

cos Theta/4 cos theta/4 - sin theta/4 sin theta/4.

- math -
**Reiny**, Thursday, May 9, 2013 at 1:41pmrecall

cos 2A = cos^2 A - sin^2 A

you have that pattern

cos(Ø/4)cos(Ø/4) - sin(Ø/4)sin(Ø/4)

= cos^2 (Ø/4) - sin^2 (Ø/4)

= cos (Ø/2)

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