Question

12. Find the exact value of sin(2x) if sin(x)=-1/2.

sin(2x) = 2sin(x)cos(x)

Answer 1

if sinx=-1/2, then cosx=sqrt(1-1/4)=sqrt(3/4)=sqrt3 /2

sin(2x)=2*(-1/2)(sqrt3 /2)
= -1/2 sqrt3