Вычислите сos 5п/12+cos п/12

Question

Вычислите
сos 5п/12+cos п/12

Answer 1

2cos[(5π/12+π/12)/2]*cos[(5π/12-π/12)/2]=2cosπ/4*cosπ/6=
=2*√2/2*√3/2=√6/2