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December 21, 2014

December 21, 2014

Posted by **Kara** on Monday, April 9, 2012 at 12:27pm.

- Pre Cal -
**Steve**, Monday, April 9, 2012 at 12:41pmcos(75) = cos(90-15) = sin(15)

sin(15) = √((1-cos(30))/2)

= √((1-√3/2)/2)

= 1/2 √(2-√3)

or

sin(15) = sin(45-30)

= sin45cos30 - cos45sin30

= 1/√2(√3/2 - 1/2)

= (√3-1)/(2√2)

I'll leave it to you to demonstrate that the two values are equal . . .

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