#cos( (5pi)/12)+cos((2pi)/3-pi/4)#
#=cos( (5pi)/12)+cos((8pi-3pi)/12)#
#=2cos( (5pi)/12)#
#=2 sqrt (1/2(1+cos( (5pi)/6))#
#=sqrt (4xx1/2(1+cos(pi-pi/6))#
#=sqrt (2(1-cos(pi/6))#
# = sqrt (2(1-sqrt3/2)#
# = sqrt(2-sqrt3)#
# = sqrt(1/2(4-2sqrt3))#
# = sqrt(1/2((sqrt3)^2+1^2-2sqrt3*1))#
# = sqrt(1/2(sqrt3-1)^2#
# = ((sqrt3-1))/sqrt2#