Question

what is the value of sine 120​

Answer 1

Explanation:

120=180−60

By using:

sin120=sin(180−60)=sin60=(√3)/2=0.867

also,

120=60+60

By using:

sin(2x)=2sinxcosx

sin120=sin(60+60)=2sin60cos60=2√3/2∗1/2=(√3)/2=0.867

also,

120=90+30

By using:

sin(90+x)=cosx

sin120=sin(90+30)=cos30=(√3)/2=0.867

Answer 2

sin 120

= sin(90+30)

= cos 30

= √3/2