Use the unit circle and the fact that sine is an odd function to find the following.

Question

if sinA=-1/3 then find sin(-A)

Answer 1

  sin A = – 1/3

Even-Odd Identities

sin(– A)  = – sin A

sin(– A)  = – (– 1/3)      ( given  sin A = – 1/3)

sin(– A)  = 1/3

 

           

Answer 2

if sinA=-1/3 then sin(-A)=-sinA

Recall: even-odd identity sin(-x)=-(sinx)

sin(-A)=-sinA 

Substitute sinA =-1/3 in the equation.

sin(-A)=-(-1/3)

sin(-A)=1/3.