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What is the exact value for cos(pi/12)?

1 Answer

Apr 27, 2016

#sqrt(2+sqrt(3))/2#

Explanation:

#color(blue)(cos(x/2)=+-sqrt((1+cos(x))/2))#

We know that #cos(pi/6)=sqrt(3)/2#.

So, #cos(pi/12)=sqrt((1+sqrt(3)/2)/2)=sqrt((2+sqrt(3))/4)=sqrt(2+sqrt(3))/2#

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