Question 577832
13pi/12 = pi + pi/12 --> 3rd Quad
sin(13pi/12) = -sin(pi/12)
In degs, = -sin(15)
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Use the half-angle formula
= -sin(30/2)
-sin(15) = -sin(30/2)
= {{{-sqrt((1 - cos(30))/2)}}}
= {{{-sqrt((1 - sqrt(3)/2)/2)}}}
= {{{-sqrt(2 - sqrt(3))/2}}}