Question 875407
How do i find the exact value of the product 
cos[5pi/24] sin[11pi/24]
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Identity: {{{sin(s)cos(t)=(1/2)(sin(s+t)+sin(s-t))}}}
sin[11pi/24]cos[5pi/24]={{{(1/2)sin(16pi/24)+sin(6pi/24)=(1/2)(sin(2pi/3)+sin(pi/4))=(1/2)(sqrt(3)/2+sqrt(2)/2)=(sqrt(3)+sqrt(2))/4}}}
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calculator check:
set calculator to radians
cos[5pi/24]* sin[11pi/24]≈0.786566
exact value as calculated=(√3+√2)/4≈0.786566