Optics Homework: Solving for Refractive Index and Critical Angle

[dinhjeffrey]

Homework Statement

#56

Homework Equations

index of refraction = sin(Θincident)/sin(Θrefraction)

The Attempt at a Solution

yeah i think Θincident is 30 degrees but i don't know how to solve for Θ of refraction. sorry, my teacher didnt teach me optics yet, and she assigned problems for hw...

 

[rl.bhat]

If you draw a normal on ac at the point of incidence, the angle of incidence is 60 degrees. If it is the critical angle C then refractive index μ = 1/sin(C).