Question 923217
Use the half angle formulas to find exact value:
SIN 210 degrees
COS 60 degrees
***
{{{sin(x/2)=sqrt((1-cosx)/2)}}}
{{{sin(210)=sin(420/2)
=-sqrt((1-cos420)/2)
=-sqrt((1-0.5)/2)=-sqrt((0.5)/2)=-sqrt(0.25)=-0.5}}}
..
{{{cos(x/2)=sqrt((1+cosx)/2)}}}
{{{cos(60)=cos(120/2)
=sqrt((1+cos120)/2)
=sqrt((1-0.5)/2)=sqrt((0.5)/2)=sqrt(0.25)=0.5}}}