Question 140797
cos(pi/12)cos(3pi/4) - sin(pi/12)sin(3pi/4)
=((sqrt(3)/2)(-sqrt(2)/2))-((1/2)(sqrt(2)/2))
=-sqrt(6)/4 - sqrt(2)/4
={{{(-sqrt(6)-sqrt(2))/4}}}
=-.965926
.
Ed