Can someone answer these and show work ? ?

3. n=1.31. So using Snell's Law of Refraction, n1sinθ=n2sinθ. Your second theta should be 15 degrees instead. The angle is ALWAYS from the vertical. Since n of air is just 1, n2=(sin45)/(sin15)=1.31.

4. This is a bit interesting, the way YOU set this up. Because I am a physicist, the dashed line for refracting angles should be perpendicular to the object's surface. Whether that is how you are told by your instructor, or your own doing, I digress. Anyway, Snell's Law again, n1sinθ=n2sinθ. N of air is 1 at an angle of 90 degrees. So 1=sin90 for both shapes. Your angle for the triangular prism is 55 degrees, so n=1/sin(55). For the funky looking shape, your angle should actually be 90-35. ANGLE IS TO THE DASHED LINE, NOT THE SURFACE. So this n is 1/sin(55) again.

You got this