cos^2(π/4+π/6)+cos^2(π/4-π/6)+1/2[cos(5π/12+π/12)+cos(5π/12-π/12)]=cos^2(π/4+π/6)+cos^2(π/4-π/6)+1/2[cos(π/2)+cosπ/3]=2cos^2(π/4)cos^2(π/6)+2sin^2(π/4)sin^2(π/6)+1/4=2*1/2*3/4+2*1/2*...