## bfoster1 Group Title How do i decide which reference triangle to use for sin-1 (sin 3pi/10)? one year ago one year ago

1. NoelGreco Group Title

Do you mean$\sin^{-1} (\sin \frac{ \pi }{ 10 })$?

2. NoelGreco Group Title

oops 3pi/10

3. bfoster1 Group Title

yes I do

4. NoelGreco Group Title

First, make sure that the angle is in the domain of the inverse sine function [-2pi,2pi]. Then remember that the sin generates a number, and inverse sin generates an angle - in this case the same angle you took the sin of.