sin105=sin60cos45+cos60sin45
=(√6+√2)/4
sin60=√3/2 cos45=sin45=√2/2 cos60=1/2
sin120=sin30=1/2
cos120=cos30=√3/2
sin120加cos120=1/2+√3/2=(1+√3)/2
sin105=sin60cos45+cos60sin45
=(√6+√2)/4
sin60=√3/2 cos45=sin45=√2/2 cos60=1/2
sin120=sin30=1/2
cos120=cos30=√3/2
sin120加cos120=1/2+√3/2=(1+√3)/2