Sin11pi/12*cos23pi/12

Răspuns :

=[sin(11pi/12+23pi/12)+sin(11pi/12-23pi/12)]/2=sin34pi/12+sin(-12pi/12)=sin(2pi+5pi/6)+sin(-pi)=sin5pi/6+0=sin(pi-pi/6)= cospi/6=rad3/2.