求sin8分支π×cos8分支π的值?

求sin8分支π×cos8分支π的值?
求sin8分支π×cos8分支π的值?

求sin8分支π×cos8分支π的值?
原式=12*[2sin(π/8)cos(π/8)]
=1/2*sin(2*π/8)
=1/2*sin(π/4)
=√2/4

sinπ/8×cosπ/8
= (1/2)sinπ/4
= √2/4