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August 28, 2014

August 28, 2014

Posted by **mathfailure** on Tuesday, November 20, 2012 at 12:08pm.

- 15-75-90 triangle?? -
**Damon**, Tuesday, November 20, 2012 at 12:15pmsin 15 = sin 30/2 = sqrt ([1 -cos 30]/2)

cos 15 = cos 30/2 = sqrt( [1 + cos 30]/2)

but

we know cos 30 = (sqrt 3)/2

plug in

then

sin (90-t) = cos t

and cos (90-t) =sin t

to get sin and cos of 75

if you need tangents use tan = sin/cos

- 15-75-90 triangle?? -
**mathfailure**, Tuesday, November 20, 2012 at 12:19pmok ty alot

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